Janus VR allows the use of custom multiplayer servers for any room. The Janus VR client will create a new connection to the specified multiplayer server if a connection does not exist, and in addition subscribe to the URL on that server (to listen to and broadcast user events which happen in the room). The custom multiplayer server is specified by adding server and port for the Room.
http://janusvr.com/docs/build/roomtag/index.html#Room
server - (default "presence.janusvr.com") Set to the domain name or IP of the custom multiplayer server for the room.
port - (default "5566") Set to the port of the custom multiplayer server for the room.
rate - (default "200") Set to the update rate (in milliseconds) for connected clients to send updates the multiplayer server.