When a client operates at a high framerate on a dedicated server, their player movement will become desynced with the server. This manifests in different ways on different versions. In 4.21, it causes intermittent desyncs, causing the character to jitter and teleport around when the server corrects the movement. In 4.22 and onward (tested in Main CL#5915479) the player's movement will become completely desynced and no longer replicate.

This has been determined to be caused by background network packets saturating the connection so RPCs and properties can't replicate.

Regression?: No
This occurs in 4.21

Steps to Reproduce
  1. Create a new Third Person Template project
  2. Enable Dedicated Server and set the number of players to 2 in the Play settings
  3. Press Play
  4. On one of the viewports, run the console command "stat fps" and "t.maxfps 300"
  5. Begin to move around on that same client.
    in 4.21: The client will begin to jitter and teleport around at times, becoming desynced intermittently with the server.
    in 4.22 and 4.23: The client will no longer be replicating movement at all
    Expected: The client moves around smoothly without any hitches or jitters.

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Affects Versions4.214.224.23
Target Fix4.23
Fix Commit6594270
Main Commit6843774
CreatedApr 17, 2019
ResolvedMay 21, 2019
UpdatedJun 7, 2019