My netplay isnt working

[Dreaden07]

Everytime I try to join a game with multiplayer the onlything I see is "Failed to connect server:could not communicate with host".
But everytime I host a game it works for some reason people are saying its because of my wifi but my wifi works good and it works for multiplayer games.                                                                                  If you know this problem from dolphin please tell me how to get rid of this problem