I'm talking about Steam Ports, some games actually connect through a query port and have also other ports for the game traffic (ARK, ConanExiles, Valheim).   They initially connection is done through the query port and the answer from the query port actually provides the game ports which are read from the game config files and if you have different port inside and outside the container that simply can't work. The issue here is that you can basically see the game in the Server Brow