Error joining a switch to PS4 (Minecraft)?

I've been playing Minecraft with someone on the Playstation for some time now. When I'm (switch) the host, everything works perfectly. If my buddy (PS4) is the host, I search for the server forever (see picture). I'm already in the game with my buddy but I can't play.

What can I do?

Try this more often or else you have to be the host, then it could work

I've tried it a thousand times. And it is an existing map that he wants to show me. The map is a little older.