All Actors, including characters, have a Net Cull Distance (NCD). It helps to determine if the replicated actor is relevant. It helps to visualize it as a sphere around the actor. By default its 150m (225000000.0 cm^2).
Large maps need a higher NCD. If I want to be able to snipe out to 1Km I need a NCD of 10000000000.0 cm^2.