To explain it further, portforwarding will improve your gaming experience and it will make your NAT type Open by opening the appropriate ports for the game and your console. However, you will be needing to contact your Internet Service Provider for them to manually open the ports in your router.
By the way, these are the ports you will be needing to open on your router:
IW (PS4) - TCP 80, 443, 1935, 3074, 3478-3480 UDP 3074, 3478-3479
IW (Xbox One) - TCP 53, 80, 3074 UDP 53, 88, 500, 3074, 3544, 4500
IW (PC) - TCP 3074, 27015-27030, 27036-27037 UDP 3074, 4380, 27000-27036
Restart your router afterwards then check again in-game.
Thank me later.
You shouldn't need to contact your ISP, they won't do much for you. If your router is DMZ capable, you forward the ports yourself (Google your router for instructions). But first you need to set the console up with a static IP to forward the ports to. These are the Xbox ports
OK This may sound convoluted, but it USUALLY works for anybody I've talked to with Nat issues.
ESPECIALLY if your XB says Open but Cod doesn't.
You need MW Remastered.
(I'll explain later why)
Step 1: Open MW Remastered
Step 2: Search for a multiplayer match
Step 3: The moment it finds a lobby, hit your guide button and load up BO4(or any other CoD you are having the issues with.) and make sure you don't close MW remastered before loading up the other CoD
Step 4: Profit.
This usually works because for whatever reason MW and MW remastered used a more aggressive Port Request than newer Cods which don't seem to be proactive in how they request ports...
It may take one or two tries but it usually works when there aren't any real networking problems...
You SHOULDN'T really ever need to forward ports, and DMZ is also usually overkill, but sometimes it's the only way.
I hope this helps somebody out there.