xivzy I don't quite understand the issue. Can you not join or can you join but have issues once you joined? Can you describe things better especially when and what exactly? I can't understand if the issue is joining the server or where you are etc.
I'll assume the issue is with joining, make sure to run a base game map, not a DLC, just in case you don't have DLC installed.
Also maybe the host's local IPv4 changed which can make the port forward rule not work anymore so check that