VPN don't work

Integrasul

Hi, we have a VPN configured, using L2TP.

It's not frequently used, but the last time it was working, 1 month ago, maybe…

But now it's showing a error message when trying to connect using windows VPN.

Error message: "Unable to connect to Palhoça Headquarters. L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer."

I have tried to connect using three different connections but same error ocurred.

Someone can help?

Zyxel_Melen

Hi @Integrasul,

Thanks for the privilege. I found some failed logs which are related to the phase 1.

And I can use my laptop to connect the VPN to your firewall. Therefore, I think this issue is more likely related to the client side.

Could you help to check these things?

1. The PC have updated to the latest Windows update? This is to avoid old Windows update cause L2TP connection issue.
2. Could you help to check the Windows registry "AssumeUDPEncapsulationContextOnSendRule" has been changed to Value "2"? The path is "HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Services > PolicyAgent"
3. Could you help to delete the VPN connection profile and add it again?

Zyxel_Melen

Hi @Integrasul,

I understand that you have changed the PC to crosscheck. However, these PCs might tested in the same network. Please help to create "AssumeUDPEncapsulationContextOnSendRule" if you don't have one. And step 3 I mentioned is to use the Windows built-in VPN creator to add the VPN profile.

Zyxel_Melen

Hi @Integrasul,

Could you enable Zyxel support access for checking?

[Nebula] How to turn on Zyxel Support Access? — Zyxel Community

Integrasul

Ok, I have enabled now.

Zyxel_Melen

Hi @Integrasul,

Thanks for the privilege. I found some failed logs which are related to the phase 1.

And I can use my laptop to connect the VPN to your firewall. Therefore, I think this issue is more likely related to the client side.

Could you help to check these things?

1. The PC have updated to the latest Windows update? This is to avoid old Windows update cause L2TP connection issue.
2. Could you help to check the Windows registry "AssumeUDPEncapsulationContextOnSendRule" has been changed to Value "2"? The path is "HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Services > PolicyAgent"
3. Could you help to delete the VPN connection profile and add it again?

Integrasul

Hi, I didn't find this registry entry

Also, we tried in three different PCs here, that used to work in the past

Zyxel_Melen

Hi @Integrasul,

I understand that you have changed the PC to crosscheck. However, these PCs might tested in the same network. Please help to create "AssumeUDPEncapsulationContextOnSendRule" if you don't have one. And step 3 I mentioned is to use the Windows built-in VPN creator to add the VPN profile.