Why is there only one server that doesn't function properly?

Why do all servers (when testing in Roblox Studio) function normally however, there is always one server that just doesn’t fire the print statements or just doesn’t receive players Data or doesn’t fire anything at all?


When testing in Roblox Studio, it will only start one server, and start multiple clients. When you start it with 2 players, there will be 4 tabs: studio, server, client1 and client2.