How do find the port number for game server?

Hello.

I am new to game servers and lenode. I was able to go though the steps of sshing into my server, updated debian, setup ssh, and made sure that vhserver was started/running (for Valheim).
However, I have no idea what port number to use or where to find it.
I have used "sudo iptables -L" and that gave me quite the output, but I couldn't figure out what could be a port number.
"grep ssh /etc/services" and "grep services ssh" gave me a smaller output, but none of those numbers worked when I tried to log into my valheim server.

Any help would be most appreciated.

Thank you.