Where a general question: how does it work with webhoster like Nitrado multiple Minecraft servers on one port, because I know one server on one port
They have multiple IP addresses that point to a server or to virtual machines on the server, but several things on the same port do not work at the same time
Very easily!
Not at all!
E.g. An MC server occupies the standard port 25565.
If you start with the same port then the console only says "*** FAILED TO BIND TO PORT * .25565 ***" and would switch itself off immediately.
Even if, how should the minecraft client know which server you want to connect to?
They have an IP pool that points to a server. There the IPs are distributed to containers. Everyone gets one or two. But these are ALWAYS different. This means that multiple game servers can run on the same ports on one root, because each game server has its own IP.
You can change the port in the server.properties. I don't know if Nitrado does the same, but at least this would be a way to let two servers run on one IP over different ports