I want to start learning to write a simple game server emulator in C#. The game works LAN but it gets LAN disconnected when internet drops so some sort of keepalive is implemented. I can copy the files to another device and it works online without a login etc so there is no online authentication but as soon as internet drops the LAN game goes down to so i need to emulate the online update server or something like that to prevent that from happening. (spotted with Wireshark etc)

I don't have much experience , just created a simple tcp client/server console app but in this case I ofcrs will only need a server one in combination with custom dns. Any tips on where to start? Does someone have an example game server emulator? or update server emulator?