Part of multiplayer is the real-time streaming of data between clients. In the Drawing Sample Scene, this is implemented using Unity's built-in NetworkManager, which requires clients to be connected to the same local network via WiFi.
A big limitation of this scene is the impossibility to do multiplayer on cellular network, or on WiFi networks with a firewall configured to block such connections. For this reason we added an alternative implementation of that sample scene, using Photon.
Photon is a popular service for cloud-based real-time data streaming, available as a Unity plugin known as PUN (Photon Unity Networking). The steps below describe the additional steps to configure Photon properly in order to use the Photon Drawing Sample Scene.