Multiplayer sof2 works fine on my PC when I play at my friend's house (he has a Netgear VPN router of some kind). When I try to play at home I keep getting the INVALID_CD_KEY message. I know my key is valid but I've read that you get this message when your network connection isn't quite right. I guess my D-Link DI604 is the problem. I've tried manually opening the right ports but still see the same message. Does anyone have this router or know what might be wrong? Thanks!