Can't connect to friends game

So I wanted to play with 2 of my friends on Horizon 2 and it didn’t work because we could not join the same game once someone else had joined it. So I joined my first friend, I got in perfectly, but my second friend said it was unreachable. I think it is that me and my second friend can’t get in the same game together because no matter who hosts the session and no matter who joins first we can’t get in the same session. Is there any way around this?
Have just portforwarded will get back with results as soon as possible

Something I forgot to mention is that we had tried Horizon 1 and still couldn’t join each other

Port forwarding my console worked so the problem has now been solved