make sure your router ALWAYS assigns the same tcp-ip address to your computer, open your PC's command prompt and type: ipconfig /all - the physical address is the mac address you'll need for this step - log into your router and look for 'reservation' now reserve the address for your PC.(described for PC but i guess it basically works for xbox and PS3 too) To solve the MW2 issue you need to do three things only: It's hard to believe how much crap is posted these days, when it comes to Modern Warfare's NAT status > strict / open.Īnd nope - I wouldn't turn on my router's UPnP function.