Quick answer: Godot 4 MultiplayerSynchronizer properties not updating on clients after host changes? Replication config needs sync nodes whose paths resolve - validate Resource paths point to live nodes.

Server moves a chest. Clients see the chest in its original position. MultiplayerSynchronizer is on the chest but not syncing.

Validate replication paths

Open the SceneReplicationConfig resource. Each entry's NodePath must resolve relative to the synchronizer. Drag-drop in the editor; don't type paths manually.

Set Authority correctly

Synchronizer needs set_multiplayer_authority(server_id). Default is the local peer; clients don't broadcast.

Enable visibility filters

For interest management, set visibility_filter. Otherwise the synchronizer broadcasts to all peers including those out of range.

“Replication configs are static. Paths and authority both need to be right at construction.”

Build a debug HUD that lists active synchronizers and their authority. Multi-peer sessions are easier to debug with visible state than with debug prints.