I assume, on this screenshot is the character, and you changing colors for it, so why you GetPlayerPawn(0)->GetStuff instead of get it from actor components? Just drag and drop mesh to graph, or type Get Mesh.
PlayerController(0) is player local with index 0, basically first one connected, PlayerPawn(0) is the same thing and i guess, at this point, you understand why client one does not getting updated.