Connecting to friends / Hosting for friends

[wishlord 10]

Hello there, I've looked on the forums and if Im posting this in the wrong section then please move my thread.

So I've been playing with friends on dayz / arma2:OA servers with no problems at all, we can both connect to private servers and official server and everything is fine.

However when he tries to connect to my server (temporary one) he sometimes get the option to type in the password, and then it says connecting failed. Sometimes it only shows a black screen saying Joining game, then returns to multiplayer menu

and says "Connecting failed".

The same thing happens when I try to join his server.

I would think it would be a port problem, but heres the strange thing for me.

So its him and me yeh, we got more friends, lets call them 1 and 2 in this example.

If I host a server he cant join me, neither can 1, but 2 have no problem joining me.

If he host a server I cant join him, neither can 2, but 1 can connect.

So its sort of like we were divided in groups.

things we have tried:

Opening ports on my router.

Updating the game and verifying the cache.

Manually downloaded BE and installed it.

We can play together on others server but not eachothers.

Any help is very welcome.

Thanks.