Multiplayer Not Working

[Crioliix]

IMPORTANT NOTICE
Before you comment, please note that i have already tried the following and it still doesn't allow me to connect:
Port Forward 34197
Allow Factorio through firewalls
Hamachi/Evolve etc...
Reinstalling the Game
Getting the latest version
Verifying the game cache

Basically whenever i try and connect to my friends multiplayer servers, it gives me the notice "Could not establish network communication to server."
Similarly, if i try to host the game, it tells me it is "unable to determine external ip address, others may not be able to connect."

If anyone knows how i can resolve this issue then please tell me because one of the main reasons i bought the game was to play with friends.

[impetus maximus]

can you connect to public games from the in game server browser?

[Crioliix]

I mean public and private games.

[bk5115545]

Sounds similar to these bug reports.
viewtopic.php?f=182&t=34390
viewtopic.php?f=49&t=33964

Attach your factorio-current.log after you've gotten the error. It helps the devs a lot.