ok u need to enable dmz. you need the last digit of ur lan ip to put in the box. usually it will be 10.0.0.1 or 10.0.0.2 or whaetver, dependin on how many computers on your network.
if you go start, run, and in the box type cmd then hit enter, the command line will come up. type ipconfig and hit enter, and you should get ur lan ip
type the last digit in the private ip box, so the address is the same as wat u got in ipconfig, and hit enable. then apply changes and save it
now ur router will be completely open, you will be able to play hoi2 and a lot of other things will run better and faster too. dont let noobs tell u dmz makes ur pc more vunerable, it doesnt, no one is gonna wanna hax ur computer lol