We are two friends who want to play Heroes of Might and Magic 2, 3 or 5 together in online multiplayer mode over internet using a TCP/IP connection.
As we are not happy with third party solutions like Tunngle and Gameranger, we decided to use our VPN server for this purpose.
We both can connect to VPN server and obtain virtual local IP addresses through VPN server. I use L2TP connection and he uses OpenVPN connection. It is a Softether VPN server so it supports both. There is no problem with our VPN connection.
However Heroes of Might and Magic 3 does not recognize the IP assigned by VPN server, instead it detects our real local IP address from our ethernet devices.
This same problem occurred to me while I am using a Windows (8.1) for this purpose, and also to my friend, who runs the game via Wine.
My question is, how can we prevent this game to take our real local IP into account and recognize only our virtual local IP addresses?