How do I get the MasterServer to work properly?

I've tried using MasterServer.RegisterHost and then MasterServer.PollHostList()to find a list of already running games. I do use the same game name in the MasterServer.RegisterHost method and MasterServer.RequestHostList method. Also, it shows that I have a public ip address, so I don't think NAT punchthrough or anything else like that is the problem. Another thing is, that anyone can connect with me if I give them my direct ip address and they connect through that.

Also, I made it off that zero to hero m2h tutorial guide.

Any ideas?