|If you've tried following multiple tutorials then I suspect we won't be likely to help you here.|
What I can say is, if there is a firewall enabled and running on the computer hosting the game, you will want to disable it or at least make a rule allowing the traffic on whichever port through.
If you've done that as well as tried creating a proper port forward there's not much else I can tell you.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.