Knowledge Base

Question

I have a USG which is behind a NAT router and gets a private IP from the NAT router.

The USG is set up as a L2TP server.

However, I can establish L2TP tunnel from my iPhone but Windows client cannot.

How to resolve it?

Answer

This reason is that deftault the Windows client is disabled for establishing L2TP tunnel behind NAT router.

You can improve it on your Windows client:

(1) Create a .txt file.

(2) Copy the following into .txt and save it.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PolicyAgent]

"AssumeUDPEncapsulationContextOnSendRule"=dword:00000002

(3) Change .txt file as .reg.

(4) Run .reg file as administrator.

After these steps, the Windows client should be able to establish L2TP tunnel which behind NAT router.