unsolvable VPN trouble. Please help!

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Guest

Hello!

Despite all those attempts I have made so far I cannot solve the following
problem on my own.

I have got a laptop running XP with SP2. Whenever I try to establish a VPN
connection to a remote server I always get a VPN error 800 or 651. The latter
one occurs after having set the connection type to PPTP-VPN using the XP-VPN
client.
I have tried using default settings, modified them one by one but it always
refused to work. The strange thing is: shutting down the firewall and
disabling all security options I could find doesn’t make it any better. I’m
really running out of ideas why it doesn’t work properly, especially because
I tested the very same connection on another computer standing next to me
(based on Windows Server 2003) several times and it worked just fine every
single time.
Thus any router problems can be excluded. I also used another operating
system on my laptop to see if it would be working fine with it and it did!
There were no problems establishing the connection under Linux so we can also
exclude a NIC hardware failure.

As a matter of fact the only explanation I can think of by now is the
service pack 2. I have also heard about people experiencing similar problems
after installing it.

Please let me know if you have any idea or remedy for this issue. I’m really
on the verge of a nervous breakdown because of all the time I’ve spent so far
on finding a solution.

I really appreciate all of your help!

Thank you in advance.
 
Some months ago I serviced a SONY VAIO laptop with a similar seemingly
inexplicable problem. I tried everything. Finally, adjusting the MTU per
"HOW TO: Change the Default Maximum Transmission Unit (MTU) Size Settings
for PPP Connections or for VPN Connections"
http://support.microsoft.com/?kbid=826159 resolved it. It's a long shot,
but maybe worth a try.
My notes on that service are not available at this moment, , but I believe I
ended up with the suggested 1400 MTU.

A few questions (based on some past troubleshooting of odd VPN issues) -

- Have you made sure that there is nothing else open that might be using the
Internet connection when attempting to connect to the VPN (including any
spyware parasites)?
- Is any AOL software installed on this machine?
- What kind of Internet connection are you using? (cable, DSL? what
provider).
 
Hello again!
First of all, thank you very much for your quick response.
Some months ago I serviced a SONY VAIO laptop with a similar seemingly
inexplicable problem. I tried everything. Finally, adjusting the MTU
per
"HOW TO: Change the Default Maximum Transmission Unit (MTU) Size Settings
for PPP Connections or for VPN Connections"
http://support.microsoft.com/?kbid=826159 resolved it. It's a long shot,
but maybe worth a try.
My notes on that service are not available at this moment, , but I
believe I
ended up with the suggested 1400 MTU.
Click to expand...

I've tried this out with various values for both ProtocolMTU and TunnelMTU
without success. I even pushed them up to a maximum of 1500. All in vain.
A few questions (based on some past troubleshooting of odd VPN issues) -

- Have you made sure that there is nothing else open that might be using
the
Internet connection when attempting to connect to the VPN (including any
spyware parasites)?
Click to expand...

Yes. Quite certain about that. I always keep my machines clean. Besides, no
further security software such as virus scanner etc. is running. I can also
be sure that it’s not a firewall issue since I’ve been running these tests
with and without it but it hasn’t change a thing.

- Is any AOL software installed on this machine?
Click to expand...
I’ve never ever even thought of using AOL. ;-)

- What kind of Internet connection are you using? (cable, DSL? what
provider).
Click to expand...

I reside in a fast Ethernet based LAN which is itself connected to a
backbone leading to my ISP. I normally obtain a private IP within a range of
10.*.*.* per DHCP. NAT is then used to map my address to a public one thus
connecting me to the internet.
I hope that’ll do as an answer.


Thank you in advance!

Best regards.
 
You're welcome. It sounds like you've already done a great job of
troubleshooting, and I'm frankly baffled along with you. The fact that the
VPN worked with Linux leads me to think that there might be some problem
either with the NIC drivers or TCP stack specifically affecting PPTP. I'd
be tempted to try a different NIC with the laptop and if that fails, if
feasible, maybe try to use a sniffer to see what's really going on lower
level. Another possible thought is resetting the TCP/IP stack as described
in
How to reset Internet Protocol (TCP/IP) in Windows XP
http://support.microsoft.com/default.aspx?scid=kb;en-us;299357
--
 
Hello!
You're welcome. It sounds like you've already done a great job of
troubleshooting, and I'm frankly baffled along with you.
Click to expand...

Yes, I have and besides being baffled I'm also pretty desperate by now.
The fact that the
VPN worked with Linux leads me to think that there might be some problem
either with the NIC drivers or TCP stack specifically affecting PPTP. I'd
be tempted to try a different NIC with the laptop and if that fails, if
feasible, maybe try to use a sniffer to see what's really going on lower
level. Another possible thought is resetting the TCP/IP stack as described
in
How to reset Internet Protocol (TCP/IP) in Windows XP
http://support.microsoft.com/default.aspx?scid=kb;en-us;299357
--
Click to expand...

Resetting the TCP/IP stack was actually a good advice. But guess what! It
didn' help. Unfortunately. I've also tried out to reset winsock ending up in
the same old result.

You know what, I've been suspecting SP2 of being my scapegoat since the very
beginnig. Now, I see that I was right. Instead of losing even more time with
sniffing around on a lower level I'd better try to remove SP2 to see if it
works without it.
Nevertheless, if you have any further ideas on all this, please let me know.
I'd appreciate that!

Thank you very much for your time and patience!

Best regards.
 
Hello again!

Just wanted to mention that I've also tried to use another NIC with the same
effect.
Thus, neither the TCP/IP stack nor the NIC (or its drivers respectively)
seem to be responsible.
 
Resetting the TCP/IP stack was actually a good advice. But guess what! It
didn' help. Unfortunately. I've also tried out to reset winsock ending up
in
the same old result.

You know what, I've been suspecting SP2 of being my scapegoat since the
very
beginnig. Now, I see that I was right. Instead of losing even more time
with
sniffing around on a lower level I'd better try to remove SP2 to see if it
works without it.
Nevertheless, if you have any further ideas on all this, please let me
know.
I'd appreciate that!

Thank you very much for your time and patience!

Best regards.
Click to expand...

I'm out of ideas at the moment other than an in place Windows reinstallation
(with slipstreamed SP2) or, as you note, trying the SP2 uninstall.
I've also seen the reports re. SP2 causing some problems along these lines,
but have not run into it myself. (One or two reports speculated about a
problem with the Windows Firewall even though it was shown disabled.) I
use a PPTP-VPN connection on the SP2 computer I'm using right now to connect
to VPN's at 2 businesses I service. I've also done a number of SP2
installations for their employees computers which access their VPNs, without
any problems, so if it is SP2 related it must involve some particular
combination of conditions.

Good luck, and please let us know if the SP2 removal does the trick..
 
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