This was the easiest way I opened my NAT for gaming on the Technicolour tg582n router.
I was stuck on strict NAT on Call Of Duty Ghosts on PS4 and searched the net for answers. I read you have to port forward etc, and do other complicated things to get open NAT type. I'm not thick but it was all above my head to start with and sounded quite complicated and a bit of messing about.
Anyway, to cut a long story short, I read about game mode on this site and decided to try it. I turned it on but was still showing strict NAT so all I did was un-tick the unpn box just to see if that did anything. Started Call Of Duty again and noticed I had open NAT. Simples, ha. I can now join my mates for a game of COD online. Cool. After nearly 6 months gaming alone.
Just thought I'd share my experience with you all. Hope it helps. Wish I'd not wasted time reading and researching port forwarding as it isn't needed. The router does it all automatic for you.
I'll try to put instructions up later if anyone gets stuck. Got to rush off to work. Here's the quick instructions. Other people might be able to explain better than me and in more detail.
Open your browser and type address for your router, mine was
http://192.168.1.254. You don't really need to type the http part in. Just the address.
Click on advanced settings and log in, then find which port your console is plugged into on your router. Click modify settings. Click on gaming mode to enable it. Un-tick unpn box. If you got Call of Duty load it up and it should say NAT type open. Should only take a few mins of your time to do.
Let me know if it works for anyone please. Thanks.
p.s. if anyone can explain better how to do it please feel free to add info