OT: Comcast cable woes

[Dave C.]

I know this is OT for here, but this is where all the really smart techie
types hang out, so I figure I've got as much chance of finding help in this
ng as anywhere else.

Several months ago, I
switched to comcast cable modem for high speed Internet service. It works
OK, but slows down at night. I can live with that. But it's got another
problem that's really annoying. Every once in a while (once a day,
usually), my Internet connection dies. Define "dies", you say? Well. . .
(Motorola SB5100 cable modem)
- Four steady green lights, one flashing orange "pc/activity" light
- Can not load ANY web page
- No error message
- Sometimes web pages start to load (I'll get some graphics near the top),
but never finish
- unplugging modem and rebooting computer has no effect
- releasing and renewing IP has no effect
- While web pages are not loading, tech support can successfully ping my
modem (so they claim anyway)
- If I try to tracert any major domain, the tracert times out, but only
after several "hops"
- 25% or greater packet loss on ping to any major domain
- Cable tech has been out twice, says signal strength (both ways) is good

Some more information that may or may not be helpful (probably not):

The system is a AMD XP2500 homebuilt with an Epox brand nforce2 chipset
motherboard using 100 speed ethernet built into mainboard. It's running XP
Pro SP1 with all updates as an OS with 1GIG of RAM. I've noticed the same
problem if I hook up a laptop to the cable modem, so I don't think it's my
computer. I run Tiny Personal Firewall, but killing that doesn't help. For
a while, I had a Zyxel Prestige 314 (aka Netgear 314) router in the mix.
But taking the router out didn't change anything.

The Motorola SB5100 modem is leased from Comcast, and was brand new when
they first hooked it up. I am now on Earthlink Cable modem service
(Earthlink through Comcast). So my IP is different, but the symptom is the
same.

Has anyone experienced similar problems? If so, what did you do to get it
fixed? -Dave

 

[jpsga]

I have been delighted with ComCast and am sorry you don't share the joy.
Could you ask them to swat out your cable modem? Since it is a lease and
potentially their problem.
DSLReports.com has a nice tool for looking at your TCP/IP setting
etal.Worth the trip.
http://www.dslreports.com/

Jim

 

[Pat Blank]

The Motorola SB5100 modem is leased from Comcast, and was brand new
when they first hooked it up. I am now on Earthlink Cable modem
service (Earthlink through Comcast). So my IP is different, but the
symptom is the same.

Has anyone experienced similar problems? If so, what did you do to
get it fixed? -Dave

Does the modem have one of those small reset buttons that you have to
poke with a pen? Try holding the reset button in for a few seconds.
Check the modem manual for reset instructions.

 

[Dave C.]

Does the modem have one of those small reset buttons that you have to
poke with a pen? Try holding the reset button in for a few seconds.
Check the modem manual for reset instructions.

Hey, good catch. According to the manual, it does have a reset button. I
doubt if it will help, considering how many times I've killed power to the
thing. However, at this point, I'm willing to try anything. -Dave

 

[nooneimportant]

I"m also on comcast, and did have issues every couple of days... exactly as
described, everythign just times out. Every now and then I had success by
pushing the standby button on front of modem, then pushing it again after a
few seconds... don't know how it worked, but it did. Still have problems
every week or so, but not as often as it was. Leads me to think its CableCo
side network issues not local issues. In our area comcast is killing all
analog signals, forcing everyone to digital (we already were), and since
they killed analog to our local loop i haven't seen as many mysterious
"downages". Just dawned on me to check out my model number... its a
Motorolla SB4100 modem, so yours may or may not have the standby button.
As much as i hate to have it go down now and then, its far more reliable
than ANY dial up service i've used....

 

[feroce]

Has anyone experienced similar problems? If so, what did you do to get it
fixed? -Dave

I had pretty much the same problem. Turns out that the cable modem was
faulty. Try swapping in a different modem and see if that helps.
Also, buy your own modem. It's a lot cheaper in the long run...

feroce

 

[Ralph D.]

I know this is OT for here, but this is where all the really smart techie
types hang out, so I figure I've got as much chance of finding help in this
ng as anywhere else.

Several months ago, I
switched to comcast cable modem for high speed Internet service. It works
OK, but slows down at night. I can live with that. But it's got another
problem that's really annoying. Every once in a while (once a day,
usually), my Internet connection dies. Define "dies", you say? Well. . .
(Motorola SB5100 cable modem)
- Four steady green lights, one flashing orange "pc/activity" light
- Can not load ANY web page
- No error message
- Sometimes web pages start to load (I'll get some graphics near the top),
but never finish
- unplugging modem and rebooting computer has no effect
- releasing and renewing IP has no effect
- While web pages are not loading, tech support can successfully ping my
modem (so they claim anyway)
- If I try to tracert any major domain, the tracert times out, but only
after several "hops"
- 25% or greater packet loss on ping to any major domain
- Cable tech has been out twice, says signal strength (both ways) is good

Some more information that may or may not be helpful (probably not):

The system is a AMD XP2500 homebuilt with an Epox brand nforce2 chipset
motherboard using 100 speed ethernet built into mainboard. It's running XP
Pro SP1 with all updates as an OS with 1GIG of RAM. I've noticed the same
problem if I hook up a laptop to the cable modem, so I don't think it's my
computer. I run Tiny Personal Firewall, but killing that doesn't help. For
a while, I had a Zyxel Prestige 314 (aka Netgear 314) router in the mix.
But taking the router out didn't change anything.

The Motorola SB5100 modem is leased from Comcast, and was brand new when
they first hooked it up. I am now on Earthlink Cable modem service
(Earthlink through Comcast). So my IP is different, but the symptom is the
same.

Has anyone experienced similar problems? If so, what did you do to get it
fixed? -Dave

Can't speak to the 5100, but... the 4100 allows you to look at this address
http://192.168.100.1/ to read your own power and noise ratio stats and
what-have-you at whatever point you are having the trouble. There is also a
Log page where your modem is recording any errors that can be very helpful.
I'd guess this address works on yours as well.

Also... if your TV picture is shaky at one end or the other of the channel
range at the same time your connectivity sucks... this will tell you whether
it may be a connector issue or something. Check all your in-home connectors
for tightness and be sure that your first splitter is *before* any TV (ie...
cable comes through wall to a T, one goes to modems with *nothing* else on
that series and the other one or two go to any TVs with *no* modems in those
series). If you are properly configured (don't assume you are because a
cable tech did it... he might be on a busy day, not making his 'appt.
windows' or hoping to meet the other installers in the area at the donut
shop at 10:15), a bad picture suggests a physical interference, which may
raise your noise:signal ratio or suggest a bad connection at the pole or
some other thing that very often are affected by times or odd circumstance.

Tracerts and pings *to* a point only tell you how your upload route looks.
You need to look at 'reverse' traces to see exactly where your speed is
tanking.Try these for reverses from several servers on several backbones.
Use as if to see which of their servers would give you the best performance
as a prospective customer (they may set off firewall alarms, they are
tracing *to* you): http://www.giganews.com/comps/line_info.mhtml Here's
another good reverse site
http://www.easynews.com/slow/trace.phtml?ip=24.53.189.47 or
http://sitka.triumf.ca/cgi-bin/nph-traceroute or
http://www.supernews.com/trace/ .

My guess is that they have over-sold your neighborhood and the local CMTS is
not holding up to the traffic, but that is purely pulling it out of my arse
based on what you report. Overall speed drops are noticeable at night, but
you may have bandwidth issues at other times, too. Pages only half loading
and then stalling may be a sign that your speeds are OK for moments and bad
for others, as in when too many people on your CMTS download at the same
instant.

When you do the above tests, have Word open and copy/paste the results into
a file and note the time and day. Do the tests when running good and bad for
comparison and see if you don't find a pattern (bet you will). Also run
speed tests from Speakeasy sites (various ones) at the same time and paste
those, too. When you have a bunch of days or weeks recorded to establish
that this is a time-related phenomenon, find out the name of the local cable
guys' supervisor and e-mail him the results day after day until they do
something about it, but be patient as these CMTS issues are very complex and
expensive to remedy. Splitting systems generally only happens for the
squeaky wheels no matter who the provider is. **Cable service degrades as
more users are added until a new CMTS is added** so if you have good friends
in the area who can also duplicate this and complain, then you'll get faster
results.


Look at the simple stuff like the connectors, first.



HTH

 

[Dave C.]

Can't speak to the 5100, but... the 4100 allows you to look at this address
http://192.168.100.1/ to read your own power and noise ratio stats and
what-have-you at whatever point you are having the trouble. There is also a
Log page where your modem is recording any errors that can be very helpful.
I'd guess this address works on yours as well.

(snip)

Thanks for all the great information. Now I'm just waiting for the
connection to die again so I can run some more tests on it. -Dave