Hello, yeah i see what you mean now haha thank you a lot.
For the ones with the same issue :
Have to separate the Line Trace (which Run on Server) and the VFX (which is Multicast)
- in “Play as Listen Server”, the Line trace is only replicated for the server
- in “Play as Client”, the Line trace is replicated for each client
So in my case i want to create a multiplayer game without a player hosting, so that’s good.