Connection Issues playstation

Trying to create a online squad with a mate on PlayStation, game accepts invite, says connecting, but then never connects to their game we have tried both of us being hosts and it’s the same problem.
This issue started yesterday and we are still unable to connect

I’m playing on PS5
Mate is on PS4

Maybe that is the problem, but I don’t know.
In the past for me and my mate (both ps5) helped:

The client closes the game and is on dashboard, then accepts the invitation and the game starts and connects.

If the client already was ingame, it never worked. Since dark skies it works additionally, if the client just starts the game, but doesn’t continue his session. If you as a client already are in a session, exit to main menu and close the game completly.

Just another question:
You both have PS+?

We have tried restarting the game, changing hosts, restarting the console, both have current PS+ We have tried exiting to the menu, tried joining from Freind’s list, and via invite, nothing seems to work

What about other games? Do they work?
What about your network settings? Nat-Type?

All other games work, even Fallout 76 of all things

Matchmaking was working after the last update but suddenly stopped on sunday

Game versions (ingame main menu) are the same for ps4 and ps5?

We once had the situation, that xbox version and game pass version had different numbers and weren’t able to play with each other + plus some more risks.

Both updated to the latest version, there is no PS5 specific version of the game it’s PS4 backwards compatible