I can't join a group with my friends, and my friends can't join mine.
My NAT connection is Moderate, my friends connection is Moderate also.
They can invite each others but i can't play with them.
I can play the game online alone just fine.
I tryed to play this since 9/02 but the issue continues.

My router has uPnP enabled.

I and my friends aim was to play together when the game came out. But actually seems to be impossible. And i doubt we'll buy the game if this issue isn't fixed before beta ends.

Feel free to ask me further questions to solve this bug.