Check out an open-source tool shared by the Ubisoft team.
Ubisoft made Mixer, their real-time collaboration system developer for Blender, available open-source. The free tool lets users work on the same scene in real time.
The company has been developing Blender add-ons since they started using it as the main DCC application for broadcast animation.
Mixer, the newly released tool, allows teams to set up a broadcasting server which deals with scene data and lets individual users connect via IP. It features the ability to create rooms to work on individual collaborative projects.
Please note that the content is deleted when all participants leave, so you have to save projects manually or make rooms remain open with no users.
You can learn more on GitHub.