i have been hosting pkmn and naruto games to see which one to start playing if they dont have a server but my friends wants me to test his out but it says "World opened on network port 1204.
end of line corruption: attempting conversion...
BYOND hub reports port 1204 can be reached by players."
You need to learn how to forward your port. Look on your router and get it's exact model. Now look up on google port forward for that model.

Basically your router has ports for traffic but you have to direct that traffic to individual computers on the network. Your goal in this case is to direct the traffic to the computer handling the Byond game.