Multiplayer mouse world location tracing problem

Ok, so I’ve been having problems with authority and player controllers, my game uses the mouse for rotation of a ship on a 2D plane, but the world is 3D, the camera itself is at a birds eye view. So when you move the mouse around the screen, the ship’s rotation follows it. Now that works perfectly fine in singleplayer. However, with multiple clients running, they’ll all turn around on one client and not update on the other, or if I set it up differently with a tick event they all judder horribly other than the one you’re controlling which is fine. Another version ends up with them only rotating on the server, so I’m confused and at my wicks end.

I realise I’m probably missing something simple, but I’ve looked around and can’t seem to find a way to fix it yet. Thoughts and suggestions would be very helpful and welcome. Thanks.