Problem when trying to host! (Warcraft 3: Reign of Chaos)

Faced with this problem, Played with my brother,I hostel all okay! And what happened was that the next day we want to play and then when I make him says the Game that you want to join, not found. Your administrator may have disabled it or you have not correctly entered the name. Thought maybe the router lost,everything looked fine,rebooted the computer again,put the file Gate. And all gone..surprised Ya But now again this problem,but nothing helps..don't know what it is,please tell me!