Dedicated server..forget it, try this...

[Megahurt]

I tried for two weeks to host a game with my dedicated server settings... I port forwarded, i left it up for hours etc. etc. etc, No luck.

Then i discovered if you go to multiplayer, select the lobby option and create a lobby and put up your game, you can host missions with friends and play for hours without a hitch..

Well, maybe one... Dont let your buddies get discouraged if they have to try joining a few times. Time outs are often unless you do it as said below.

Heres what works best. Create the lobby. Get your buddies to join the lobby before creating the server. Then create the server, select the mission, start the battle.
They will then press start and wella. They're in.

After weeks of reading the forums and trying everything under the sun to get my dedicated server to work (i could join it on lan but no one else could--"server not responding") i finally stumbled on this under reported option. So im reporting it.
Have fun, it works.