From your perspective, UPnP (Universal Plug and Play) and port forwarding will essentially do the same thing, with the first being an automated process and the second being something you set manually. That's why you don't want to have both set at the same time on the same device because it ends up 'double NAT-ing' and everything breaks. First I'd try a cold boot of the router just to clear down the NAT table. A big chunk of the time that will actually work when the UPnP kicks in again but the problem will probably occur again at some point down the line. You could try giving your gaming device a fixed IP address and then putting it in a DMZ on your router, but for the sake of security I wouldn't advise it. It is the lazy way out though. For the best result, I'd consider putting your device on a fixed IP address, disabling UPnP on the device and then setting up port forwarding for that address on the router. This will give you the most control but takes a little while to do. You can run that alongside UPnP on the router with no issues because it will simply use the port forwarding setup for that IP as a preference.