If you can't get port forwarding to work, you can use one of those personal VPN software things. Comodo and Hamachi are two you see AI players frequently use. No forwarding and fiddling with your router is needed
(though you do need to get other players on your VPN as well, which means they will have to use the software as well)
It might not even be your router. It may be your ISP; some ISPs pretty much block all unsolicited incoming requests, which will also stop you from hosting a game online. These VPN solutions should get around that too, though.