Steam MP: ONE player can't connect to server, mods not working, etc

[Germanic Heathen]

Yo folks,

so I'm just attempting to host my first MP game with some RL friends. All seems fine except for ONE player who has several problems:
- He subscribed to two mods I recommended to him but they don't even appear in his mods tab, though they did get downloaded
- Steam friends list ONLY FOR HIM only shows me that he's online, whether he's playing Stellaris or not. When he plays other games the list shows that just fine
- try has he might, he can't connect to my game
- although he has played some SP, his steam doesn't show any playtime for Stellaris

Apparently, SOMETHING is wrong steam-wise on his side but we can't figure out what it is. Any ideas?

 

[Germanic Heathen]

Never mind we just figured it out... he had installed the game but until now never started it via the Steam client. Now that he did all works well