Simple Multiplayer Tool (v1.0) is an easy tool to make online games obviously, just drag server prefab from assets and drop it into your scene! And don't fogret to choose player prefab.  This library has demo scene.
(You don't even need the Network Helper, since the server prefab already includes all the capabilities of the Network Helper)
Docs & Source:  https://github.com/Happyfoxq/SimpleMultiplayerTool