Lion L2TP VPN Service With Windows 7

If you have a Lion server behind a NAT router (for example, an Airport Extreme or Time Capsule) that is running a VPN service you may have difficulties connecting to it with Windows 7 using L2TP despite the correct setup.

I won’t go into the deep dive on this now, but just a total quick tip. You need to change the encapsulation parameters on Windows 7. Do that by setting a registry key:

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\PolicyAgent]

…add a new DWORD value:

“AssumeUDPEncapsulationContextOnSendRule”=dword:00000002