Are you using a torrent client? If so what I do is tick 'Enable UPnP' in the torrent client and then log into the router and tick 'Enable UPnP'. Another way is under 'Firewall Rules' make sure that port forwarding is set up for whichever one your torrent client is using.
Aside from what was mentioned above; it should work; what exactly is the problem you are getting. This might help civ iv port forwarding