Problem with VPN Configuration of USG Flex 100

snopy

Hello,

today I tried to set up VPN access for my iPhone and my Windows PC on my new USG Flex 100 firewall. I used the Wizard and selected the L2TP connection.
After that I downloaded the profiles and installed them on my iPhone and my Windows laptop. The iPhone connected successfully, but the Windows PC did not. I get the error that the connection to the VPN server cannot be established.

After changing some settings and testing a bit, I then tried the Wizard again, this time using the left option (IKEv2). With that one you have to configure everything manually on the clients, since no config file is provided. However, that did not work either.

I have already spent quite some time on this.
What kind of information do you need so you can help me?
Maybe it makes sense to first discuss the best practice setup – how most people configure it so that it actually works.

Details:

• USG Flex 100 running the latest firmware
• Windows 11 is up to date as well
• I tried using the built-in Windows VPN settings

Thanks for your help!
Marius

Zyxel_Melen

Hi @snopy

In order to check your issue, could you help to provide the error message about the connection failure?

Normally, iPhone can connect, but Windows can't, this could be Windows OS issue, which block L2TP VPN connection by the register, ensure the "AssumeUDPEncapsulationContextOnSendRule" DWORD value is set to '2' in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PolicyAgent registry path, and reboot your PC. But you mentioned IKEv2 also can't connect. What's the difference in the uplink between your iPhone and the Windows PC?

Zyxel_Melen

Hi @snopy

In order to check your issue, could you help to provide the error message about the connection failure?

Normally, iPhone can connect, but Windows can't, this could be Windows OS issue, which block L2TP VPN connection by the register, ensure the "AssumeUDPEncapsulationContextOnSendRule" DWORD value is set to '2' in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PolicyAgent registry path, and reboot your PC. But you mentioned IKEv2 also can't connect. What's the difference in the uplink between your iPhone and the Windows PC?

snopy

Thanks for your help,
i solved Problem last night with change something on my infrastrucure and Modem. :)