VPN File Sharing Problems

G

Guest

I have a VPN tunnel established between my location in PA and our other
location in Indiana using 2 D-Link 804HV's. The tunnel is established and has
been solid for about a week. The problem is when I attempt to access the
shares on the remote PC's or when performing a RDC. Please keep in mind, that
I had this VPN working perfectly when the 2nd VPN router was at my house
about 10 miles away.

I can view all the shares by typing the IP address into an Explorer address
bar. I can navigate through all the folders and get down to viewing the
individual files. The problem comes when I attempt to do anything with the
files, such as copy them to my PC or view their properties. Sometimes
Explorer locks up and other times I receive a message stating that the
network path is no longer valid. I can then immediately go back to another
explorer window and navigate right back to the PC's shares.

The other problem is that I receive a black screen when attempting a RDC.
Everything I read about this problem points to the MTU value. I performed the
recommended command of

ping ipaddress -l 1500 -n 50 -f

Sometimes everything is fine and other times I receive the message "Packet
needs to be fragmented, but DF sent". I attempted to lower the MTU value in
the D-Link, but the only setting for MTU applies under the WAN menu and
didn't change anything.

I am, however, able to access their VPN router from my location with no
problems.

Running a pathping, I am finding losses at two different places of 100% if I
ping by the WAN address given to the router by the ISP. If I pathping
directly to the PC (192.168.0.56) I don't have any loss. I have contacted
AT&T about line quality problems. They sent out a tech, who apparently placed
a DSL filter on the entire building and was able to get everything
straightened out, but I'm not so sure. (I wasn't there, since I work in the
PA office and the Indiana office is the one with the problem). I wasn't able
to access their router consistently until the tech had finished his work.

Why would I be able to access the router....everytime....but not the PC's
behind the router??

I have also attempted to physically dial down the MTU setting on the NIC
using DRTCP and had no luck.

I tried adding a static route on both sides althought I'm not sure it was
necessary because we are both on the same subnet and have a basic network
setup. Modem -> Router -> Switch. I just found out that I can transfer a
file from my PC to the remote PC in Indiana, but I receive the following
error:

Cannot copy filename: The specified network name is no longer available.

But the file actually transfers????

Can someone help me??? Thanks and sorry for the long post, I just wanted to
try and cover all the steps I have taken to this point.

Oh, I have also attempted to physically dial down the MTU setting on the NIC
using DRTCP and had no luck.
 
R

Robert L [MVP - Networking]

Correct, that sounds like MTU issue. You may need to modify the MTU on windows. This how to may help.
How to change mtu
By default, Windows Server 2003, 2000 and XP use a fixed maximum transmission unit (MTU) size of 1500 bytes for all PPP connections and use a fixed MTU size ...
http://www.howtonetworking.com/VPN/mtu1.htm - Similar pages

How to determine the optimal MTU
In a case you may need to modify the MTU size and wonder how to determine the optimal MTU for your system. You can use ping command to do so, for example, ...
http://www.howtonetworking.com/VPN/mtu4.htm


Bob Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net
How to Setup Windows, Network, VPN & Remote Access on http://www.HowToNetworking.com
I have a VPN tunnel established between my location in PA and our other
location in Indiana using 2 D-Link 804HV's. The tunnel is established and has
been solid for about a week. The problem is when I attempt to access the
shares on the remote PC's or when performing a RDC. Please keep in mind, that
I had this VPN working perfectly when the 2nd VPN router was at my house
about 10 miles away.

I can view all the shares by typing the IP address into an Explorer address
bar. I can navigate through all the folders and get down to viewing the
individual files. The problem comes when I attempt to do anything with the
files, such as copy them to my PC or view their properties. Sometimes
Explorer locks up and other times I receive a message stating that the
network path is no longer valid. I can then immediately go back to another
explorer window and navigate right back to the PC's shares.

The other problem is that I receive a black screen when attempting a RDC.
Everything I read about this problem points to the MTU value. I performed the
recommended command of

ping ipaddress -l 1500 -n 50 -f

Sometimes everything is fine and other times I receive the message "Packet
needs to be fragmented, but DF sent". I attempted to lower the MTU value in
the D-Link, but the only setting for MTU applies under the WAN menu and
didn't change anything.

I am, however, able to access their VPN router from my location with no
problems.

Running a pathping, I am finding losses at two different places of 100% if I
ping by the WAN address given to the router by the ISP. If I pathping
directly to the PC (192.168.0.56) I don't have any loss. I have contacted
AT&T about line quality problems. They sent out a tech, who apparently placed
a DSL filter on the entire building and was able to get everything
straightened out, but I'm not so sure. (I wasn't there, since I work in the
PA office and the Indiana office is the one with the problem). I wasn't able
to access their router consistently until the tech had finished his work.

Why would I be able to access the router....everytime....but not the PC's
behind the router??

I have also attempted to physically dial down the MTU setting on the NIC
using DRTCP and had no luck.

I tried adding a static route on both sides althought I'm not sure it was
necessary because we are both on the same subnet and have a basic network
setup. Modem -> Router -> Switch. I just found out that I can transfer a
file from my PC to the remote PC in Indiana, but I receive the following
error:

Cannot copy filename: The specified network name is no longer available.

But the file actually transfers????

Can someone help me??? Thanks and sorry for the long post, I just wanted to
try and cover all the steps I have taken to this point.

Oh, I have also attempted to physically dial down the MTU setting on the NIC
using DRTCP and had no luck.
 
G

Guest

I didn't think this would apply, because it isn't a PPP connection. I tried
to modify the MTU value within the router itself, but the only adjustment is
under the WAN setting tab. Would that adjustment apply for the VPN as well?

I'll try your suggestion and post back. Thanks!
 
G

Guest

I tried editing the registry like you suggested and had the same problems.
I've been doing random pingpaths throughout the day and see that the packets
are being lost at the same two routers every time. Is it possible that the
IPS has WAN ping requests blocked in fear of a DDos attack?

Is there anyway to bypass certain routers when creating the tunnel? It
looks like if I could get the route of the tunnel to "go around" those 2
routers that I might not have a problem.

Also, is there any possibility of watching the packets as they go through
the tunnel and find out what is really happening to them?

Thanks!
 

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