I this point I don’t know what to say but you are almost there!
You just need to choose an event that will automatically fire after the player joins and call that change_skin server RPC from there.
In my game I did something even weirder but I think you shouldn’t have to and it would be harder to make it work: I had the server send out Client RPCs to all the playercontrollers, to ask them what their skins were, and they responded back with the skin and their Player ID, and did the change_skin on the server from there. I did it that way when the server opens the level, but like I said that sounds like it’s adding another step that you probably don’t need.