This article provides a high-level overview of the new, experimental MultiServer Replication Plugin and covers some frequently asked questions.
https://dev.epicgames.com/community/learning/knowledge-base/xBvk/unreal-engine-experimental-an-introduction-to-the-multiserver-replication-plugin
It seems with UE_WITH_REMOTE_OBJECT_HANDLE = 1, engine fail to compile under 5.6 code. It seems currently unusable.