Issue Creating/Joining Blitz Games.

I play MNC with my older brother, who lives with me, and my younger brother, who lives in Kansas. When my younger brother makes a game for us, my older brother and I can't join it. We click on it, enter the password, and after a brief time loading we all get kicked out to the menu without even having seen the arena.

If my older brother or I make the game, our brother in Kansas can't join it because no matter what we try, the game is created as a LAN instead of through the Internet. However, my older brother and I have no trouble joining and playing the game.

We're not sure what the problem is, or whether it's with us or him. Would creating a server with the HLDS tool resolve the issue, or is there a simpler method than the HLDS tool available?