[CCR1036] LAN uploading speed almost half of the download speed

RouterOS General
1

CCR-1036, fully Netinstalled with new Router 6.44.2 firmware and downgrading version by version without success.

  1. LAN ports all connected by one bridge.
  2. When uploading to NAS, the uploading speed is almost half of the downloading speed. (60MB/s vs 110MB/s)
  3. To rule out the hard drive speed limit (SSD on local machine, NAS raid with two 1GB port bonding, can max around 220MB/s), I attached them to Dell switch,
    The download / upload speed are symmetric 109MB/s – 110MB/s with NAS one 1GB LAN port or 1GB LAN port X 2 bonding. (limited on local machine 1GB LAN port)
  4. When connected back to CCR-1036, the uploading remains 50MB/s-60MB/s.
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2

Also this time i uncheked all other options, only remains 1000M Full for interface → Ethernet Auto negotiation, to make sure the interface won’t wrongly negotiate and run in other speed option.

I am basically run out of all measures to troubleshooting this situation, as i also email customer service without any reply.

Any more detailed analysis tools of the LAN port advised?