As you may know recent Microsoft Windows Update for W10/W11 broke the L2TP/IPSEC VPN
reddit topic KB5009543 - January 11, 2022 Breaks L2TP VPN Connections : sysadmin (reddit.com)
There are only two workarounds on the client side -
2) disable IPec tunneling
L2TP VPN fails with error 787 - Windows Server | Microsoft Docs
But as Microsoft confirmed problem in L2TP is the unknown Vendor ID sent from L2TP server.
Windows 10, version 21H2 | Microsoft Docs
So, question is very simple - is there any option to change/remove Vendor ID in VYOS vpn settings?
VYOS 1.2 202101 Rolling release.