[UNET] NetworkServer.Spawn disconnection when using network latency simulation

Steps to reproduce:
1. open attached project (make sure latency simulation is activated)
2. build and run as host
3. editor as client
4. mash 'Space' key for 10-20seconds (cubes get spawned)

- Disconnects client without any error message

note: image and repro mp4 attached

Reproduced: 5.3.4p4, 5.4.0b15
Reproduced but got an error message: 5.2.4f1