Random Network drop out issue

[BigAl.NZ]

Hi Guys,

I will attempt to explain this problem as best I can. I recently got
high speed access to the net via a wireless dish. The dish has some
client equipment in it and is connected to my PC via wired Ethernet.

My PC has been assigned a static IP for the network, and because we are
behind a router its not a real world IP.

The problem is that rnadomly I loose my connection to the internet. I
still show a connection on the LAN indictaors on the status bar.

Now I find that if I click Repair on the context menu for that
connection everything is fine again.

This can happen a few times a day. The service provider swears its
nothing at his end, and the fact that I have to repair to fix it kinda
supports this theory. I dont know much about the gear but that its
Trango. I am on XP SP2 with the latest IE7.

Anyone able to shed any light pease?

Thanks

-AL

 

[Elmo]

Hi Guys,

I will attempt to explain this problem as best I can. I recently got
high speed access to the net via a wireless dish. The dish has some
client equipment in it and is connected to my PC via wired Ethernet.

My PC has been assigned a static IP for the network, and because we are
behind a router it's not a real-world IP.

The problem is that randomly I lose my connection to the internet. I
still show a connection on the LAN indictaors on the status bar.

Now I find that if I click Repair on the context menu for that
connection everything is fine again.

This can happen a few times a day. The service provider swears it's
nothing at his end, and the fact that I have to repair to fix it kinda
supports this theory. I don't know much about the gear but that it's
Trango. I am on XP SP2 with the latest IE7.

Anyone able to shed any light pease?

Open the Device Manager, locate the Ethernet card, open Properties and
turn off the power option to "Allow the computer to turn off this device
to save power".

 

[Malke]

Hi Guys,

I will attempt to explain this problem as best I can. I recently got
high speed access to the net via a wireless dish. The dish has some
client equipment in it and is connected to my PC via wired Ethernet.

My PC has been assigned a static IP for the network, and because we are
behind a router its not a real world IP.

The problem is that rnadomly I loose my connection to the internet. I
still show a connection on the LAN indictaors on the status bar.

Now I find that if I click Repair on the context menu for that
connection everything is fine again.

This can happen a few times a day. The service provider swears its
nothing at his end, and the fact that I have to repair to fix it kinda
supports this theory. I dont know much about the gear but that its
Trango. I am on XP SP2 with the latest IE7.

The first thing to try is to disable power management on your computer's
network adapter. Go to Control Panel>System>Hardware>Device Manager. Expand
the network devices category and find your ethernet adapter. Double-click
it to get its Properties. Click on the Power Management tab and uncheck the
box that says "allow Windows to turn off this device when not in use". See
if that helps and if it does not, then please post back with a bit more
detail about your particular computer's hardware and its virus/malware
status.

Malke

 

[Jeff Liebermann]

(e-mail address removed) hath wroth:

I will attempt to explain this problem as best I can. I recently got
high speed access to the net via a wireless dish. The dish has some
client equipment in it and is connected to my PC via wired Ethernet.

My PC has been assigned a static IP for the network, and because we are
behind a router its not a real world IP.

Does it also have a statically defined gateway IP?

Are the DNS servers listed or are they set to obtain their addresses
from the ISP router? (This is important. Check the settings).

The problem is that rnadomly I loose my connection to the internet. I
still show a connection on the LAN indictaors on the status bar.

The connection you're seeing in the system tray is the ethernet
connection, not the wireless connection. You could block the wireless
signal completely and it will still show that you're plugged into the
Trango wireless bridge.

Now I find that if I click Repair on the context menu for that
connection everything is fine again.

Impossible. All the you're doing is repairing the ethernet
connection. Others have suggested checking the power save setting. My
guess(tm) is that you won't find a "wireless" connection in the:
Control Panel -> Network
window and that the ethernet device on your unspecified model computer
does not have a power save feature.

However, the question remains, why does it work for you. My guess is
that you can get the exact same effect by simply unplugging the
ethernet cable, waiting a few seconds, and plugging it back in. Does
this also fix the problem?

This can happen a few times a day.
The service provider swears its nothing at his end,

- How many times is "a few"? Numbers please.

- Is there any pattern to the outages? For example, does it only
happen during normal eating times, when microwave ovens tend to be
operating? Is it different on weekends?

- Are you using the computer when it dies, or have you left it idle
for a long while?

- You may have lost the internet, but have you checked if you've lost
your ISP's gateway? Determine the gateway IP address by running:
start -> run -> cmd <enter>
ipconfig
Then try pinging the gateway when it's working, and when it dies:
ping ip_address_of_gateway
If it does NOT work when it goes dead, you have lost your wireless
connection to the WISP.

- Does it *REQUIRE* that the connection be repaired, or does it fix
itself if you wait long enough? How long? Use:
start -> run -> cmd <enter>
ping -t ip_address_of_gateway
and watch the error messages. When normal results return, it's back
to working. If the downtime is approximately that of cooking a
microwave dinner, I think we have the culprit. There also ping tools
which will help run this test continuously:

and the fact that I have to repair to fix it kinda
supports this theory.

No, it doesn't. For example, if the WISP's DNS servers were screwed
up and not responding, it would appear that you can't surf the
internet, while all that's happening is that you can't resolve the
domain names into IP addresses. Try obtaining the IP address of a
popular web site and using that instead of the name to see what
happens when it does down. To get the IP address, run something like:
ping www.yahoo.com
then try the resultant IP address in the form:
http://66.94.234.13
If your wireless ISP is using some kind of DNS load balancing scheme,
or you have one of the three possible DNS servers typed in wrong, you
might see some problems.

It may also be something as simple as the time delay required to
repair the connection if the outages are fairly short in duration.

I dont know much about the gear but that its
Trango. I am on XP SP2 with the latest IE7.

Trango has a support forum. I suggest you ask about signal strength
and interference problems.
<http://www.trangobroadband.com/forum/default.aspx>
If the diagnostics returns that you have a marginal signal to your
WISP, you may need to tinker with the antenna, or do some
repositioning to avoid interference.

Anyone able to shed any light pease?

If shedding light is anything like shedding fur on a dawg, I don't
think you will want it.

My guess(tm) is that if you're absolutely sure your XP setup is
correct, that your signal is good and strong, and that you have line
of sight to your WISP, I would then look into interference problems. A
"few" times per day sounds like a microwave oven. It does not need to
be yours as anything along the line of sight (and beyond) to the ISP
will cause problems. See the FAQ at:
<http://wireless.wikia.com/wiki/Wi-Fi#Interference>
for a laundry list of possible culprits.

 

[BigAl.NZ]

Gee - Thanks for all the great suggestions so far!!

I have turned off power management for the adapter as instructed, but
as i can not re[licate the problem at will, I will just have to wait
and see.

Does it also have a statically defined gateway IP?
Yes

Are the DNS servers listed or are they set to obtain their addresses
from the ISP router? (This is important. Check the settings).

They are listed.

Impossible. All the you're doing is repairing the ethernet
connection. Others have suggested checking the power save setting. My
guess(tm) is that you won't find a "wireless" connection in the:
Control Panel -> Network
window and that the ethernet device on your unspecified model computer
does not have a power save feature.

I am running an Asus A8N32-SLI Deluxe motherboard with a AMD Athlon64
2.2Ghz 3500+ chip. The twin onboard (motherboard) ethernet adapters are
Marvel Yukon 88E8053 Gigabit Ethernet Controllers.

Under power management for these adapters I have unchecked the setting
"Allow the computer to turn off this device to save power"

However, the question remains, why does it work for you. My guess is
that you can get the exact same effect by simply unplugging the
ethernet cable, waiting a few seconds, and plugging it back in. Does
this also fix the problem?

Will try that next time it does it.

- How many times is "a few"? Numbers please.

It varies, but the average would be twice.

- Is there any pattern to the outages? For example, does it only
happen during normal eating times, when microwave ovens tend to be
operating? Is it different on weekends?

Thats a interesting point - because it has been happening in the
mornings, but also happens overnight (I am not on my computer but my
MSN is logged out suggesting a loss of connectivity)

- Are you using the computer when it dies, or have you left it idle
for a long while?

It has happened when I am using it, and I am pretty sure it has also
happened when i am not.

- You may have lost the internet, but have you checked if you've lost
your ISP's gateway? Determine the gateway IP address by running:
start -> run -> cmd <enter>
ipconfig
Then try pinging the gateway when it's working, and when it dies:
ping ip_address_of_gateway
If it does NOT work when it goes dead, you have lost your wireless
connection to the WISP.

Good suggestion.

- Does it *REQUIRE* that the connection be repaired, or does it fix
itself if you wait long enough? How long? Use:
start -> run -> cmd <enter>
ping -t ip_address_of_gateway
and watch the error messages. When normal results return, it's back
to working. If the downtime is approximately that of cooking a
microwave dinner, I think we have the culprit. There also ping tools
which will help run this test continuously:
<http://www.tools4ever.com/products/free/freeping/>

Another good suggestion - will try that too.

It may also be something as simple as the time delay required to
repair the connection if the outages are fairly short in duration.

Someone else mentioned Malware/Virus? I thought about that too - I have
had my HiJackThis log checked over at CastleCops- and I am clean. Also
running Ewido and Kaspersky - all clean.

Cheers

-Al

 

[BigAl.NZ]

Just after I posted my last message the connection dropped. So I can
now offer the following info:

When the connection first dropped I did a ping to the gateway within
about 1 min. No ping.

Then about 30 seconds of the first set of pings I pinged the gateway
again and got a return, but no connection to the internet.

Unplugging and plugging the ethernet cable back in had the same result
as repair - it allowed me to connect to the internet again.

Cheers

-Al

 

[Jeff Liebermann]

Just after I posted my last message the connection dropped. So I can
now offer the following info:

When the connection first dropped I did a ping to the gateway within
about 1 min. No ping.

Then about 30 seconds of the first set of pings I pinged the gateway
again and got a return, but no connection to the internet.

The gateway connection recovered but not the internet? Is this
wireless contrivance part of a mesh network or does your WISP use a
store and forward system for their access points? Having a radio
disappear from a mesh network will cause the network to re-route
packets around the node. That could explain why it doesn't recover
immediately.

If I really stretch my imagination, it's possible that the gateway
might be alive, but no routing if there were some manner of exotic
mesh routing protocol operating on this system. However, that's
usually not the case. Does this wireless system include some manner
of "monitor" program that is running on your computer that sends "keep
alive" packets to the WISP?

My overactive imagination can also contrive a situation where the
default route changes in response to RIP2 updates from the ISP. That
would give you a proper ping return from the gateway, but would route
all your packets to nowhere in particular. Run:
start -> run -> cmd <enter>
route print
before and after the connection drops and note the default route
listed at the bottom.

Unplugging and plugging the ethernet cable back in had the same result
as repair - it allowed me to connect to the internet again.

Ok, that's a good clue. Unplugging the ethernet connection usually
causes the ethernet connection to reset and to obtain a new DHCP
assigned IP address when plugged back in. However, you state that you
have static IP address, gateway, and DNS servers, so that's not what's
happening. Are you sure that they're static?

It's possible that the Trango radio is part of the problem. If it has
an IP address, try to ping it. If your lucky, it's one IP address
above or below your assigned IP address. However, it may not be
easily accessible from your Windoze box. Try running:
arp -a
and see if you can identify the box. Trango starts with:
00-01-DE-xx-xx-xx

My crystal ball still says it's interference. However, the question
is why doesn't it recover by itself. It should recover, but without
detailed knowledge of the wireless topology, I can only speculate.

 

[Drake]

Just after I posted my last message the connection dropped. So I can
now offer the following info:

When the connection first dropped I did a ping to the gateway within
about 1 min. No ping.

Then about 30 seconds of the first set of pings I pinged the gateway
again and got a return, but no connection to the internet.

Unplugging and plugging the ethernet cable back in had the same result
as repair - it allowed me to connect to the internet again.

Hopefully you are using high quality CAT6 cable?

 

[Bill Kearney]

I will attempt to explain this problem as best I can. I recently got

high speed access to the net via a wireless dish. The dish has some
client equipment in it and is connected to my PC via wired Ethernet.

Explain what equipment. Make, model and exact ways it's all wired together.

My PC has been assigned a static IP for the network, and because we are
behind a router its not a real world IP.

What static IP? Presumably it's also got static DNS addresses too?

The problem is that rnadomly I loose my connection to the internet. I
still show a connection on the LAN indictaors on the status bar.

Spell it 'lose'.

Now I find that if I click Repair on the context menu for that
connection everything is fine again.

Repair? With a static IP?

When it's working, try opening a cmd prompt and typing "ipconfig /all" and
post the results here. Then, when it dies, use the same command and see if
there's *any* differences.

When using the ping command, does it always return a successful ping to the
gateway? Even before doing a repair or disconnect/reconnect of the ethernet
cable from the PC to the router?

When it's working, what lights are lit on the router *and* on the back of
the PC? Does your network card in the PC have lights for connection, duplex
and speed (often color-coded)?

I'm left wondering if the wireless device isn't doing something to detect
that the PC is connected and altering the wireless link. As in, it drops
the internet link based on it thinking the PC isn't there. If that's the
case then either your PC is "doing something" that confuses the router or
the router itself is misconfigured or just plain defective.

-Bill Kearney

 

[Bill Kearney]

Hopefully you are using high quality CAT6 cable?

For the connection from a PC to a router like this that's a useless
suggestion. Plain old CAT5 would work fine. Presuming it's a good cable of
course.

 

[BigAl.NZ]

Ok guys, an update,

When I do the repair I have discovered what is fixing the problem, it
is the clearing of the arp cache.

I know this because I did a manual clear of the arp cache with "arp -d
*" and that fixed it.

I dont know much about arp but hopefully someone here can make some
conclusions about this?

Explain what equipment. Make, model and exact ways it's all wired together.

Its a Trango Fox 5310 Subscriber Unit. The ethernet cable goes from the
back of the PC into a Power over Ethernet box, out of there and up to
the roof where the Trango is. No routers at my end.

What static IP? Presumably it's also got static DNS addresses too?

Yep - take a look at a screenshot here:
http://img54.imageshack.us/my.php?image=ss1nr5.jpg

Repair? With a static IP?
Yep.


When it's working, try opening a cmd prompt and typing "ipconfig /all" and
post the results here. Then, when it dies, use the same command and see if
there's *any* differences.

Ok, here it is when its working:
--------------------------------------------------------------------------------------------------------------------------------------------
C:\Documents and Settings\Al>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : al-60c9aaef8b2d
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Marvell Yukon 88E8053 PCI-E
Gigabit
Ethernet Controller
Physical Address. . . . . . . . . : 00-17-31-38-4E-0D
Dhcp Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.168.252.1
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.252.254
DNS Servers . . . . . . . . . . . : 192.168.252.254
210.55.12.1

Ethernet adapter Bluetooth Network Connection:

Media State . . . . . . . . . . . : Media disconnected
Description . . . . . . . . . . . : Bluetooth Device (Personal
Area Netw
ork)
Physical Address. . . . . . . . . : 00-80-98-44-0B-1D
------------------------------------------------------------------------------------------------------------------------------------------------

When using the ping command, does it always return a successful ping to the
gateway? Even before doing a repair or disconnect/reconnect of the ethernet
cable from the PC to the router?

It always sends a successful ping to the gateway when working
(occasionaly 1% loss)

I did try to ping the gateway when the connection when down, and on my
second attempt I got a return, initally I thought it was just the
connection between me the gateway being fixed, but now I think the
whole connection was repaired. Sometimes it fixes itself after a few
minutes - sometimes it takes longer. Have not quite worked this out
exactely yet.

When it's working, what lights are lit on the router *and* on the back of
the PC? Does your network card in the PC have lights for connection, duplex
and speed (often color-coded)?

No router involved here - will check the PC.

I'm left wondering if the wireless device isn't doing something to detect
that the PC is connected and altering the wireless link. As in, it drops
the internet link based on it thinking the PC isn't there. If that's the
case then either your PC is "doing something" that confuses the router or
the router itself is misconfigured or just plain defective.

-Bill Kearney

Thanks Bill - will post the ipconfig /all when its not working....

-Al

 

[BigAl.NZ]

PS:

here is my arp -a result before a dropout:

-------------------------------------------------------------------------------------------------------------------------------------------------
C:\Documents and Settings\Al>arp -a

Interface: 192.168.252.1 --- 0x2
Internet Address Physical Address Type
192.168.252.254 00-02-a5-02-44-bd dynamic

 

[glen herrmannsfeldt]

For the connection from a PC to a router like this that's a useless
suggestion. Plain old CAT5 would work fine. Presuming it's a good cable of
course.

I agree, the cable quality doesn't matter much for a short cable,
but I have had some bad cables. Mostly, I believe, the contact
between the cable and the connector, even with commercial cables.

-- glen

 

[glen herrmannsfeldt]

When I do the repair I have discovered what is fixing the problem, it
is the clearing of the arp cache.

In that case, the one answer is another host trying to come
online with the same IP address. The router will then put that
host in its arp table, disconnecting you. Clearing the arp cache
will usually cause your host to arp, adding it to the router arp
table.

One I did see once on a machine with both IP and Appletalk
(ethertalk) was arp replies in both ethernet and SNAP format,
causing the router to switch to SNAP format IP that the host
would then ignore. A ping to any host not in the arp table
would cause a new arp request, and the router would then stop
sending SNAP encapsulated data. That is not likely to be
your problem, though.

-- glen

 

[BigAl.NZ]

Ok,

Here ya go, I just lost the connection, and after I lost the
connection, but before I repaired it this is what I got from IPCONFIG
/ALL and ARP -a

C:\Documents and Settings\Al>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : al-60c9aaef8b2d
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Marvell Yukon 88E8053 PCI-E
Gigabit
Ethernet Controller
Physical Address. . . . . . . . . : 00-17-31-38-4E-0D
Dhcp Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.168.252.1
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.252.254
DNS Servers . . . . . . . . . . . : 192.168.252.254
210.55.12.1

Ethernet adapter Bluetooth Network Connection:

Media State . . . . . . . . . . . : Media disconnected
Description . . . . . . . . . . . : Bluetooth Device (Personal
Area Netw
ork)
Physical Address. . . . . . . . . : 00-80-98-44-0B-1D

C:\Documents and Settings\Al>arp -a

Interface: 192.168.252.1 --- 0x2
Internet Address Physical Address Type
192.168.252.254 00-02-a5-02-44-bd dynamic

C:\Documents and Settings\Al>arp -d *

HTH?

-Al

 

[BigAl.NZ]

One more thing I had a packet sniffer, Ethereal running when it went
down and came back up - not sure if the logs from this will help?

-Al

 

[glen herrmannsfeldt]

One more thing I had a packet sniffer, Ethereal running when it went
down and came back up - not sure if the logs from this will help?

It might.

Better would be the results of arp -a on the router machine
before and after. Otherwise, if there are any arp packets just
before it dies in the ethereal output, post them.

-- glen

 

[Jeff Liebermann]

For the connection from a PC to a router like this that's a useless
suggestion. Plain old CAT5 would work fine. Presuming it's a good cable of
course.

Agreed. CAT6 is overkill. What limits high speeds is crosstalk (NEXT
and FEXT). For short lengths, such crosstalk is negligible and almost
any type of wire or cable will work.

All of the bad ethernet cables in my palatial office and trucker were
made by me. There should be a clue here, but I'll pretend to ignore
it. Most are visibly defective with:
- creative wiring
- split pairs
- bad crimp
- wrong type of RJ-45 plug
- mangled plastic seperators between pins
- partial crimp
being the main culprits. In general, commercial cables are good
enough.

 

[Jeff Liebermann]

When I do the repair I have discovered what is fixing the problem, it
is the clearing of the arp cache.

I know this because I did a manual clear of the arp cache with "arp -d
*" and that fixed it.

I dont know much about arp but hopefully someone here can make some
conclusions about this?

Weird. You didn't answer my question as to whether your wireless ISP
is part of a mesh network. If so, it would make sense that the
destination gateway might change depending on the topology of the
moment. I'll keep things simple and avoid this possibility.

The obvious question is whether the MAC address of the gateway
(192.168.252.254) changes before it disconnects, and after it
recovers. Try it before and after and see if there's a change. If it
does change, well then you'll need to do something to forcibly expire
the arp cache and ping the gateway, which should renew the entry.

However, if it doesn't change, then try this experiment. Run:
arp -s 192.168.252.254 xx-xx-xx-xx-xx-xx
to permanently set the MAC address of the gateway. If this fixes it,
my guess(tm) is that either your ethernet driver or IP stack on your
computah is having a bad day. It's suppose to send an ARP request to
the gateway immediately after it detects a connection. It's not.

I just tried to simulate your problem. I have an ancient DWL-900AP+
setup in client mode connected to the neighbors WRT54G. Encryption is
off. When I disconnect the antenna to simulate a connection loss, it
takes about 2 minutes for XP to recognize that the connection is gone.
Various services (AIM, Skype, PPTP VPN) fail prior to XP announcing a
lost connection.

When I put the antenna back and try to ping the neighbors router, it
takes about 20 seconds to re-establish the connection. Yours
apparently takes either much longer or never succeeds. I just did it
again, but this time, I had a continuously running FPING session
running. The reconnection was about 5 seconds. This is the way it
should work.

Its a Trango Fox 5310 Subscriber Unit. The ethernet cable goes from the
back of the PC into a Power over Ethernet box, out of there and up to
the roof where the Trango is. No routers at my end.

Nice:
<http://www.trangobroadband.com/products/fox5310_international.shtml>
5.3GHz. No mesh network. No microwave oven interference. Do you
have line of sight? How far away is the central access point.

Yep - take a look at a screenshot here:
http://img54.imageshack.us/my.php?image=ss1nr5.jpg

Perfect. No problems with the IP setup. I can't seem to get the
secondary DNS server to respond to my DNS queries, but it might be
firewalled to accept queries only from the WISP's network.
nslookup
Default Server: dns1.snfcca.sbcglobal.net
Address: 206.13.28.12

server 201.55.12.1

Default Server: [201.55.12.1]
Address: 201.55.12.1

www.cruzio.com

Server: [201.55.12.1]
Address: 201.55.12.1

DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
*** Request to [201.55.12.1] timed-out

This is probably unrelated to the current problem, but you should
check if your secondary DNS server is functional from your end.

It always sends a successful ping to the gateway when working
(occasionaly 1% loss)

Are the ping times (latency in msec) constant? In other words, do
they always show the same number of msec, or do they vary all over the
place? If they vary, it's a sign of interference or possibly wireless
congestion. The extra delays are signs of packet retransmissions.
Unfortunately, I can't tell where the gateway IP is located in your
WISP's network, so it's difficult to isolate just your traffic
results.

I did try to ping the gateway when the connection when down, and on my
second attempt I got a return, initally I thought it was just the
connection between me the gateway being fixed, but now I think the
whole connection was repaired. Sometimes it fixes itself after a few
minutes - sometimes it takes longer. Have not quite worked this out
exactely yet.

It requires traffic to fix itself. If the arp cache is being flushed,
it won't repopulate the ARP cache untill it sends something to the
gateway. What I find interesting is that the gateway appears to be
functional, but nothing beyond it. Try using traceroute (Windoze
tracert) to something else is going down along the path. It might be
the backhaul between the central access point and where it hits a
wired connection.

 

[Jeff Liebermann]

C:\Documents and Settings\Al>arp -a

Interface: 192.168.252.1 --- 0x2
Internet Address Physical Address Type
192.168.252.254 00-02-a5-02-44-bd dynamic

00-02-A5-xx-xx-xx is owned by Compaq Computahs:
<http://www.coffer.com/mac_find/?string=00:02:a5>
Well, that makes sense as the gateway is also a DNS server.

From your previous posting, the arp -a results are identical before
and after the disconnect. If you preload the ARP cache with:

arp -s 192.168.252.254 00-02-a5-02-44-bd

methinks I can eliminate the arp cache as a probable culprit and move
onward to whatever is preventing the connection from recovering
gracefully. As far as I can tell, your system is operating normally
except in one respect. It does not recover quickly or gracefully from
a disconnect. I'm still not sure why, but in every other respect, it
functions exactly like my quick test previously mentioned.

Also, I think you would do better to determine (or guess) why the
system is showing disconnects in the first place. My guess(tm) is
some obstructions in the path (trees, cars, excessive path) or
interference from other users of this WISP system.