How to block traffic in Windows 10 that bypasses VPN (L2TP/IPsec)?

Question

VPN

Hello.
It was OpenVPN and the Firewall was configured properly, i.e. everything went exclusively through OpenVPN - https://zorrovpn.com/articles/windows-firewall-vpn-only
The speed of OpenVPN was just terrible. The server was connected to a 100 Mbps port, and OpenVPN was barely delivering 1 Mbps. it was decided to switch to L2TP/IPsec. The speed has grown to 15-20 Mb / s, which is quite satisfactory, but a second problem has appeared, the standard Windows 10 VPN can simply turn off in the middle of work.
Therefore, you need to somehow configure the Firewall so that traffic goes only when the VPN is running. Is there an instruction on how to do this?

Answer 1

Write the simplest batch file in which you add a route to the VPN gateway via netsh, and change the default gateway to a known non-working one.
Since there is an explicit route to the VPN, the traffic will follow the route, and everything will work.
Let's say VPN is disabled - traffic goes to the default gateway, but it is unavailable - there is no Internet.
Well, the second batch file that will change everything back, for those cases when you need to work without a VPN.