Unreal Tournament 3 Port Forwarding / DMZ / Can't uncheck LAN

Error
Your network configuration is not compatible with hosting matches. Please check your router's manual for instructions on setting up 'Port Forwarding' or a 'DMZ server'.

I know i'm not the only one with this issue, and there is a fix that WORKS listed here: http://www.lanpartyguide.com/ut3.html

I must warn you, it isn't easy, but if you do it correctly it does fix the error message and let's you host a public campaign without being in the DMZ of your router.