This version of Unity is unsupported.
Removed

Network.SetLevelPrefix

Obsolete The legacy networking system has been removed in Unity 2018.2. Use Unity Multiplayer and NetworkIdentity instead.

Declaration

public static void SetLevelPrefix(int prefix);

Description

Set the level prefix which will then be prefixed to all network ViewID numbers.

This offers protection to prevent old network updates from straying from into a new level from the previous level. This can be set to any number and then incremented with each new level load. This doesn't add overhead to network traffic but just diminishes the pool of network ViewID numbers a little bit. The Network level loading page has an example of how to use this function.