The reason why you’re experiencing issues is because you’ve got your Chunk Download Rate set too high.
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You currently have the Chunk Download Rate set to 60. This allows the engine to request 60 chunks simultaneously. (Whilst the chunks vary in size) this requires approximately 16 Mbits of bandwidth.
However the peak bandwidth you achieved was ~11 Mbits/s.
This means you’re allowing the client to request more data than you have bandwidth for. This means that whilst the client is download chunks it might starve the essential realtime entity connection. If this connection is starved you will hit network issues.
I recommend you set Chunk Download Rate to “High - 30 chunks/s” or “Medium - 15 chunks/s”. This will likely not be noticeable whilst loading, but will stop the entity connection from being starved of bandwidth.