I'm transferring a lot of pictures from my Macbook Pro to a local Synology NAS (DS116), using an FTP software named Transmit.

I noticed that the upload speed is quite different between Wi-Fi and Ethernet:

  • Using Wi-Fi (ac): ~27 MB/s in FTP mode, and ~22 MB/s in AFP mode

  • Using Ethernet (via a Thunderbolt adapter): ~110 MB/s, in both FTP and AFP modes

I don't understand why the Wi-Fi transfers are so slow compared to Ethernet. Both of them should handle the maximum write speed of the disk (112 MB/s according to Synology).

Any idea about what could be slowing down the transfers when using Wi-Fi?

Notes about my Wi-Fi :

RSSI: -56 dBm

Noise: -95 dBm

TX Rate: 350 Mbps

PHY Mode: 802.11ac

Router: TP-Link AC750

  • 1
    350 Megabit per Second (Mbps) = 43.75 Megabyte per Second (MB/s). Ethernet is always faster then Wi-Fi.
    – user61744
    Sep 9, 2017 at 16:49
  • What @pjc90 said. Plus a wired connection will always be more reliable.
    – Allan
    Sep 9, 2017 at 17:02
  • I know that it's always faster :) My assumption was actually that my router allowed 750 mbps = 93 MBps, given that it's named AC750. But after checking the specs of the router, it appears that 750 is the dual-band speed... And in my case, I'm using the 5 Ghz band which is limited to 433 mbps. Plus the noise, thus the 350 mbps. So I guess the limitation comes from the router... I really thought it was faster! Thanks for your answer ;)
    – peter
    Sep 9, 2017 at 17:04

1 Answer 1


To make it an official answer:

350 Megabit per Second (Mbps) = 43.75 Megabyte per Second (MB/s). Ethernet is always faster and more reliable then Wi-Fi. So when Ethernet is available, use it.

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