1. Install Tunngle (if you haven't already)(You can do it from FoA folder or launcher)
2. Start Tunngle and Login (at the bottom of the interface)
3. Search for a Network Name (Fall of Anterfold) or select a Genre (e.g. Shooter) on the left
Double click the desired Network Name in the Network Browser that opens in the middle
Tunngle will now Join the Network.
Once the network has been joined, you should see the other active members in the Network Nick List.
4. Press Arrow (By RMB press "Configure'' and select the FoA.exe)
5. Start the game by LMB on Arrow.
In game go to "Custom Lobby" and press ''Create a Game'',don't forget to check the episode which you want play with friend.Wait your friend and after this press ''Start Match".
Go to "Custom Lobby" and from list find the game of friend.If you found it then double click on name for joining.
After every second play,you can get a crash.The only way to fix is just start the game and quit after this create the next.
Registration of account here.