UPnP has been squirrelly for me on every firmware since 378.55. I'm still running it because of that. It's worth a shot. I'm not running a PS4, but we have 3 Xbox Ones in the house. With 378.55, the port forwarding log shows all requests as it should and all three systems can be open NAT (though Black Ops 3 still goes moderate on all but one). With any firmware after that, the Xbox Live ports for UPnP show under Connections instead of Port Forwarding, and they all time out... so NAT type depends on who turned on their console first. Not really sure why that is, but that has been my experience with it.