After open TCP AND UDP ports, you should be able to connect. There's no other way. I play it very often with no problems. There's something blocking the connection most probably. Disable the router firewall if there's any. I should warn you though, the internet gameplay it's a little buggy at the time. If the connection is not good and not very fast, it will mostly break from time to time. I usually play in on the internet with friends under a solid connection.