My friend no longer comes to my Minecraft world?

I have a Minecraft problem…

Me and a friend have a Minecraft world together. I'm the host and I'm also born. My friend can only be half born. When he presses join world he has an endless loading screen but his skin is already in the world. If he "joins" it does not say in the chat that he has joined. Only when he then closes the game will the chat say that he has left the game. I play on the PS4 and he on the computer. The world is about 500 MB. Maybe someone knows the problem.

Well then he has to uninstall minecraft and reinstall it - or / and you have to turn on multiplayer

Multiplayer is on. He actually already uninstalled and installed the game, but he's doing it again now.