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L2TP VPN Fails to Contact Server

I have set up L2TP VPNs on tens of PCs without a problem.
However, I now have a PC which has the correct certificates installed but just refuses to connect. The server never registers a connection attempt from the client PC (Windows 7).
This PC is not under my control and seems to have a plethora of 3rd party utilities on it. The user is also someone who likes to meddle with the settings of their PC. I suspect that either the network ports are blocked by some other software or there is a config setting which is blocking L2TP (note that Point To Point Tunnelling Protocol does work).

Any help with diagnostics/troubleshooting would be appreciated.

Krzysztof Pytko

Looks like Advanced Firewall port blocking (?) Please, ensure that client allows for TCP 1701 (L2TP) port connection PPTP uses TCP 1723

Regards,
Krzysztof

ajmcqueen

ASKER

OK.
How do I check for that and if it is blocked how do I find out what's blocking it?

Thanks for your help.

Krzysztof Pytko

Try to use portqry2 to check if it's opened
http://support.microsoft.com/kb/832919

you can download it from
http://www.microsoft.com/download/en/details.aspx?id=17148

and how to identify what blocks it, it's not so simple. You need to check local firewall (built-in) or 3rd party firewall or anti-virus software. That's the most common issues.

Krzysztof

ajmcqueen

ASKER

Please do not close yet - will do some more tests

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ajmcqueen

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ajmcqueen

ASKER

Not really resolved but take pragmatic step of using different technology