Windows 10 VPN issue

[MartijnLangohr]

Hi guys,

I'm experiencing a problem with VPN using L2TP (with preshared key) and 2 VMs.

So here is my setup:
VM1 is installed with Windows Server 2019 and configured with RAS.
VM2 is a Windows 10-client which is part of my domain (configured on VM1).

What i'm trying to simulate is that VM2 works from home and makes a VPN connection with his/her AD-account to VM1 to use company-resources like shares and applications. VM1 has two adapters; adapter 1 is configured with Bridged Networking and adapter 2 is configured with Host-Only (for internal networking), VM2 has only one adapter which is configured with a NAT.


The thing is, with this setup i'm able to make a VPN connection with VM2 to VM1 when my host is connected to my private home network, but this doesn't work when my host is connected to my university network. VM1 doesn't get an internet connection with Bridged Networking while my host is connected to the internet. I think this is probably caused by a security policy on my university's network.

So i changed VM1's adapter 1 from Bridged to NAT and i got a working internet connection. So i also changed VM2's adapter from NAT to NAT-network to create a completely different virtual network, i'm not sure if this really creates another network so please tell me if it isn't. I updated the VPN settings on VM2 with the new IP of VM1 and tried connecting, but it failed. It gave the following error:

"The L2TP connection attempt failed because the security layer encountered a processing error during the initial negotiations with the remote computer"


I started looking online and double-checked the Security settings of the VPN but everything seems fine, but i still can't make a VPN connection..


Is there anyone here who knows what could be causing the problem?
If you guys need more information i will provide it to you.

Thanks in advance!