I would make sure you are properly port forwarding through your router, check your firewalls and check to see if you have conflicting IP addresses / ports, also with the correct protocol selected in your router options, TCP and not UDP. In the past, I have seen that one has to add a port forwarder for both protocols, and selecting the wrong one would cause it not to work.
If none of that helps, try assigning your device a static IP address through your router and then repeat the steps over again.