How to Instantiate each players in a different location without identifing each one?

Steve

I would like to know to sync data across the network, specifically, how to update a queue or a list, in the network. I tried to use a Vector3 List and remove a vector3 when a player is instantiated but the list isn't synchronized.
I also thought if a method could wait until the other players who use the same method are done but I couldn't find one