I have almost set up a server on my own on linux, but I got the always restarting problem maybe bound to port misconfiguration on firewall or sorta kind of that. However I was thinking about a possible implementation of a closed net server. We may wrap the connection message sent by client into connection manager and redirecting it into an open server storing account name. In database table we may store that account's characters and allow users to only create new characters or use the local stored characters created directly on server lobby.
Hoping on an answer, I'd like to have an advice for configuring iptables to allow connections. I'm using OVH as hosting provider.
Kind Regards