Same problem here , but I can't port forward. What firewall do I disable?
If you are on Windows, just type in "Firewall" after clicking start.
Or if you have a other program like ZoneAlarm, try disabling that.
Everyone can Port Forward, some can't do it on their own modem and need to go to a website of their ISP.
But Port Forwaring isn't necessary to being able to join. So if you haven't messed in it yet don't do it.