How to create VPN L2TP/IPSEC channel for access to one address?

Question

VPN

I need to access a service that spins on 10.*.*.*:12000, which is protected by VPN L2TP / IPSEC over the Internet (I also have the server address, login, password and key).
My attempts:
1) I can't set up this connection in Windows so that the Internet works and access to 10.*.*.*:12000 is.
I am creating a new VPN in the wizard. The VPN connection works, but the Internet drops out. If in the properties of the IP4 protocol, the VPN unchecks the box "Use a gateway to access the Internet (something like that)", then the Internet works, but the ip is no longer reachable. You need to do some sort of routing. But I don't know how. In general, I need the following:
If we access 10.xxx:12000 we go through VPN, if not, then to the standard Beeline Internet (which, by the way, is also a VPN)
2) The second option, if the first one does not work out, is to do it on VDS. I took a test VDS for 10 days with Debian on board, I connected via SSH and I don’t know what to do. How to configure this L2TP/IPSEC? I'm pretty weak on Linux.

Answer 1

Manually write the route up to 10.*.*.* after lifting the VPN, specifying the gateway on the side of the VPN server.
Suppose that the VPN server address on the Internet is 1.2.3.4, it is configured to distribute the 192.168.200.0/24 subnet to clients, it has the address 192.168.200.1 on this network, and your service is available from it on 10.1.2.3. You raise the VPN, write route add 10.1.2.3 mask 255.255.255.255 192.168.200.1, and there will be both the Internet and access to the service.