Remote Desktop Connections Intermittent

  • Thread starter Thread starter Matt
  • Start date Start date
M

Matt

Hi

I have been using remote desktop connections over VPN from my home
broadband connection (using a BT Voyager 100 USB ADSL Modem) for over
a year without any issues. A week ago, remote desktop connections to
started to fail with different errors (seemingly at random):

1. Because of a protocol error (Code: 0x10cb)....
2. The session will be disconnected. Your computer may be low on
memory.

(My computer has plenty of memory and disk space - nothing else is
running - virus free - spyware free - etc.).

The remote servers I'm connecting to are in different parts of the
country (UK), maintained by different people from different companies,
and are a combination of Win2000 and Win2003. So, I don't think it's
anything to do with the servers.

When I start to make the remote desktop connection it takes a couple
of minutes before I get the error message.

Occasionally (maybe 1 in 10), I will be able to connect for about 5
minutes before the remote desktop connection is broken (ie. the window
goes to greyscale and shows the broken connection icon in the
top-right).

Using two separate laptops (one WinXP and the other Win2000), this
error occurs from my home broadband modem. However, both laptops work
perfectly when connected through a different broadband router in my
office. They also work perfectly when connected to our office LAN.
So, it seems to be a problem with my home connection only.

To confuse matters, web browsing appears to work perfectly.

I'm stumped. I've called my ISP (BT) and of course they are claiming
that it's nothing to do with them... Does anyone have any ideas? I
feel that this has to be a problem with my home connection or my ISP.

Thanks - I'm desperate for some help!

Matt
 
Further details: VPN/RD over a dial-up (56K) connection over the same
telephone line (through the ADSL filter) works fine.

Totally confused now. :)
 
Even more details:

Taking one remote terminal server as an example, I have noticed that
if I ping the server's external IP address (say for 10 minutes) then
there is no packet loss. However, if I VPN into this remote server
then ping a local IP on the domain I'm VPN'd in to, I get 10% packet
loss (successful pings have a typical response time of 50ms). Other
users VPNing from their home connections get no packet loss over VPN.

Does this extra information help anyone to identify what is going on?

Thanks
 
Hi Matt,
Yes, it makes sense.
Summarizing:
Two laptops, connect through a usb cable to the modem.
RD fails
VPN is dodgy
HTTP (Web browsing) is ok.

Two laptops connected to office (lan ?):
No problems.

First off, there is a difference in protocols.
HTTP is robust, and based on TCP/IP. TCP will try and
recover from missing packets, before it gives up and
notifies the application (IExplorer)

VPN and RDP rely on UDP/IP.
UDP is a 'fire and forget' kind of protocol.
It is built on the assumption that:
You have a stable network connection
The application used is able to do the recovery on lost
frames.

UDP is mostly used for streaming media (internet radio,
webcams) where one missing frame isn't all that of an
issue.
Consider an rdp connection being a kind of "looking at a
moving image" of the remote desktop, it stands to reason
UDP is used. TCP would really get bogged down for the
overhead needed to create the robustness of this protocol.

So..
My guess is that you insert and yank out the usb cable to
the modem on a daily basis, prolly several times a day.
Seems to me that it's likely that either the usb cable,
or the usb port of your laptop is starting to show the
wear and tear.
It's good enough for tcp (recovering from lost frames
unnoticed) but udp is failing.

Test:
Using a third pc, with hardly used (in terms of
inserting/pulling out cable) usb ports, and try the rdp
connection.
If that fails too, then get a new usb cable.

If that solves the problem for the third pc, then test it
on the laptop.
If you still have problems on the laptop (but not on the
test pc) then you need to also slap in a new pc card with
a usb port.

Cheers,
Leo
-----Original Message-----
Even more details:

Taking one remote terminal server as an example, I have noticed that
if I ping the server's external IP address (say for 10 minutes) then
there is no packet loss. However, if I VPN into this remote server
then ping a local IP on the domain I'm VPN'd in to, I get 10% packet
loss (successful pings have a typical response time of 50ms). Other
users VPNing from their home connections get no packet loss over VPN.

Does this extra information help anyone to identify what is going on?

Thanks

Further details: VPN/RD over a dial-up (56K) connection over the same
telephone line (through the ADSL filter) works fine.

Totally confused now. :)
Click to expand...
Click to expand...
Click to expand...
 
Hi Leo

Thanks for responding and enlightening me with regards to the TCP
details.

Re your idea - it was a good one, but I've tested with several
computers, several cables, different routers, different everything in
fact. The same hardware works fine on friends' ADSL connections.

The problem also affects SSL connections. I am unable to browse to
any https sites at all. They are EXTREMELY slow and occasionally
(after a few minutes) I might get a little bit of unformatted text
back...

My ISP is as confused as I am by this. Apparently all line tests are
showing good SNR.

Does anybody have any ideas what could be causing (seemingly all)
secure protocols to be having a problem? Due to all the testing with
different hardware/sites, I'm pretty sure this problem HAS to be
outside my control.

Thanks

Matt
 
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