I have been playing Call of Duty MW3 on the PC. I'm connected wirelessly and when I do this my NAT type is open.

When I disable my wireless and connect using an Ethernet cable to same router, the NAT type is strict.

I have uPnP enabled on the router.

Is there any reason why wireless would be open and wired strict? It's the same router so I imagine it should be the same NAT type no matter how you connect to it.