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I was trying to transfer a 50 MB file to my Raspberry Pi 3 via samba and I noticed that after few seconds the transfer slows down until it stops, same thing via scp. It starts but after few seconds (5-7) the speed drops. I'm running the latest Raspbian jessie.

This is the dmesg output:

[    4.272062] usbcore: registered new interface driver brcmfmac
[    4.408506] brcmfmac: brcmf_c_preinit_dcmds: Firmware version = wl0: May 27 2016 00:13:38 version 7.45.41.26 (r640327) FWID 01-df77e4a7
[    4.418558] cfg80211: World regulatory domain updated:
[    4.418584] cfg80211:  DFS Master region: unset
[    4.418593] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
[    4.418608] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (N/A, 2000 mBm), (N/A)
[    4.418621] cfg80211:   (2457000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm), (N/A)
[    4.418633] cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (N/A, 2000 mBm), (N/A)
[    4.418647] cfg80211:   (5170000 KHz - 5250000 KHz @ 80000 KHz, 160000 KHz AUTO), (N/A, 2000 mBm), (N/A)
[    4.418661] cfg80211:   (5250000 KHz - 5330000 KHz @ 80000 KHz, 160000 KHz AUTO), (N/A, 2000 mBm), (0 s)
[    4.418674] cfg80211:   (5490000 KHz - 5730000 KHz @ 160000 KHz), (N/A, 2000 mBm), (0 s)
[    4.418686] cfg80211:   (5735000 KHz - 5835000 KHz @ 80000 KHz), (N/A, 2000 mBm), (N/A)
[    4.418698] cfg80211:   (57240000 KHz - 63720000 KHz @ 2160000 KHz), (N/A, 0 mBm), (N/A)
[    4.443235] brcmfmac: brcmf_cfg80211_reg_notifier: not a ISO3166 code
[    5.438938] brcmfmac: brcmf_add_if: ERROR: netdev:wlan0 already exists
[    5.438949] brcmfmac: brcmf_add_if: ignore IF event
[    5.443389] brcmfmac: power management disabled
[    5.962063] cfg80211: Regulatory domain changed to country: IT
[    5.962079] cfg80211:  DFS Master region: ETSI
[    5.962085] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
[    5.962093] cfg80211:   (2402000 KHz - 2482000 KHz @ 40000 KHz), (N/A, 2000 mBm), (N/A)
[    5.962101] cfg80211:   (5170000 KHz - 5250000 KHz @ 80000 KHz, 160000 KHz AUTO), (N/A, 2000 mBm), (N/A)
[    5.962109] cfg80211:   (5250000 KHz - 5330000 KHz @ 80000 KHz, 160000 KHz AUTO), (N/A, 2000 mBm), (0 s)
[    5.962115] cfg80211:   (5490000 KHz - 5710000 KHz @ 160000 KHz), (N/A, 2700 mBm), (0 s)
[    5.962121] cfg80211:   (57000000 KHz - 66000000 KHz @ 2160000 KHz), (N/A, 4000 mBm), (N/A)

And from iwconfig wlan0:

wlan0     IEEE 802.11bgn  ESSID:"Name"  
          Mode:Managed  Frequency:2.437 GHz  Access Point: XX:XX:XX:XX:XX:XX  
          Bit Rate=72.2 Mb/s   Tx-Power=31 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=70/70  Signal level=-36 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:540  Invalid misc:0   Missed beacon:0

Could be a driver issue? Router channel? What does Tx excessive retries:540 mean, too?

Update: ifconfig wlan0 reveals that i'm having several RX packets dropped (about 10%, even though disabling power management improved a bit).

In fact, sending data FROM the pi looks reasonably fast, sending TO the Pi is very slow (1-1.5 MB/s).

  • I assume it's probably because you're being limited by SD disk write speed. Unless you're trying to write to a different attached USB drive? I don't know what speeds are but I assume network transfer speed is likely way faster than the write operation to an SD disk. – dbmitch Oct 22 '16 at 19:24
  • It shouldn't, it's a 32 gb samsung evo micro sd card. Looking at wavemon via ssh it seems that the raspberry pi itself hangs, making the connection very unstable. – Matteo Oct 22 '16 at 19:42
  • Your problem is probably nothing to do with the Pi. This is likely a normal network response to network errors. – Milliways Oct 23 '16 at 0:23
  • @Milliways since you are saying the that it's not the pi, which network errors are you talking about? – Matteo Oct 24 '16 at 5:58
  • 1
    Could it be a power issue? WLAN uses quite a bit of power, there might be not enough left for the Pi, depending on how much the micro USB adapter can supply. – LeonG Mar 7 '17 at 20:32

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