I create a custom match in bo2 zombies using the tutorial and my friends double click my name and it says joining match but than nothing happens

Yes we started the match before joining, my friend noticed that when he paused it froze the background of the game (not sure if that means anything). We have both tried hosting and nothing.
These are his port forwarding settings

(Sorry for the wait I can only post every 600 seconds lmfao)

UPNP is enabled for me but not for my friend. My friend followed the instructions of port forwarding and still nothing.

Me and my friend can join random servers but when we make the private games following the tutorial we cant join each other. I have tried double clicking on their names in the friends list and the join via ip. Otherwise i have got no clue what I'm doing wrong.