From what I understood currently to do it in multiplayer using “World Composition” (replacement of World Browser) you need to:
- enable world composition in World Settings (all your levels will be used for streaming automatically it seems which can be not desired in some cases)
- disable world origin rebasing also in World Settings
- limit your total world size to WORLD_MAX radius around the world origin (+/-5km I believe)
For more info relative to World Composition in general the official page is there:
World Composition User Guide
I already tried myself with a few different streaming distances, added fog to make it look as seamless as possible etc… It works well when I run two test clients with Dedicated Server on. They both get levels loaded and unloaded correctly separately and their linked actors with them. There must still always be a persistent level of course with the players etc…