Windows 7: Hosting War3 with router

Hi I'm having problems hosting with windows 7 through a router on my laptop. It hosts fine when i plug directly into my modem, but when i add the router into the mix (wireless or wired) it won't work (my router is a Linksys WRT300N v1).

I have 6112 enabled to my ip (yes ive checked its the right ip, whether my network was an auto (where it was always .101) or when i set it manually to .105). ive done the range thing too 6112-6119 to my ip.

I've also tried DMZ to my ip. and upnp. and combos of one of the other, and both. No luck. windows firewall isn't the issue, since i could host with it on when it was plugged right into the modem (i just turned it off now anyways). And I have no other firewalls enabled.

to clarify i can host fine with windows xp on the network, and my friend hosted fine with vista on my network ... so just not windows 7...whats up? Any help is thanks cuz ive been trying to fix this for weeks