lostcaggy
Posts: 7
Joined: Wed May 16, 2012 8:56 pm

ssh slow using official wifi dongle

Sat Oct 10, 2015 3:40 pm

Hi when connecting to a RPi2, using the white official dongle, over ssh the response from the pi is very slow, letters can take a few seconds or longer to appear in the console.
Switching to an unbranded dongle everything works smoothly. Can anyone suggest a reason as to why this is and any possible fixes.
Thanks

Nautilus
Posts: 3
Joined: Sat Oct 10, 2015 6:31 pm

Re: ssh slow using official wifi dongle

Sat Oct 10, 2015 8:42 pm

Hi,

I am facing the same issue with two newly purchased RPi2's accompanied with the official Raspberry logo wifi dongles. The issue is random though, at times it works quite smoothly.

User avatar
lmarmisa
Posts: 1264
Joined: Thu Feb 14, 2013 2:22 am
Location: Jávea, Spain

Re: ssh slow using official wifi dongle

Sun Oct 11, 2015 7:39 am

Type the command iwconfig and compare both cases. You will see information about link quality, signal level or noise level.

Code: Select all

pi@rpi ~ $ iwconfig
wlan0     IEEE 802.11bg  ESSID:"xxxxxx"  Nickname:"<WIFI@REALTEK>"
          Mode:Managed  Frequency:2.462 GHz  Access Point: C4:E9:85:22:7F:6C
          Bit Rate:54 Mb/s   Sensitivity:0/0
          Retry:off   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=100/100  Signal level=100/100  Noise level=0/100
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

lo        no wireless extensions.

eth0      no wireless extensions.

pi@rpi ~ $

lostcaggy
Posts: 7
Joined: Wed May 16, 2012 8:56 pm

Re: ssh slow using official wifi dongle

Sun Oct 11, 2015 12:58 pm

these are the results of iwconfig

Code: Select all

[b]Good Working dongle[/b]
wlan0     IEEE 802.11bgn  ESSID:"TP-LINK_2.4GHz_A2CC9F"  
          Mode:Managed  Frequency:2.457 GHz  Access Point: 30:B5:C2:A2:CC:9F   
          Bit Rate=120 Mb/s   Tx-Power=20 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:off
          Link Quality=55/70  Signal level=-55 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:69   Missed beacon:0

lo        no wireless extensions.

eth0      no wireless extensions.

[b]Raspberry Pi Official
[/b]
wlan0     IEEE 802.11bgn  ESSID:"TP-LINK_2.4GHz_A2CC9F"  
          Mode:Managed  Frequency:2.457 GHz  Access Point: 30:B5:C2:A2:CC:9F   
          Bit Rate=24 Mb/s   Tx-Power=1496 dBm   
          Retry short limit:7   RTS thr:off   Fragment thr:off
          Power Management:on
          Link Quality=56/70  Signal level=-54 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

lo        no wireless extensions.

eth0      no wireless extensions.

User avatar
lmarmisa
Posts: 1264
Joined: Thu Feb 14, 2013 2:22 am
Location: Jávea, Spain

Re: ssh slow using official wifi dongle

Tue Oct 13, 2015 9:59 am

The "official" dongle is not working too quickly. The signal is not perfect, but the bit rate negotiated is low.

This command ( wget -O /dev/null https://downloads.raspberrypi.org/raspbian_latest ) could be useful for comparing the download speeds of the dongles (type ctl-c to abort):

Code: Select all

pi@rpi ~ $ wget -O /dev/null https://downloads.raspberrypi.org/raspbian_latest
--2015-10-13 11:50:50--  https://downloads.raspberrypi.org/raspbian_latest
Resolving downloads.raspberrypi.org (downloads.raspberrypi.org)... 93.93.130.39, 93.93.130.214, 93.93.128.211, ...
Connecting to downloads.raspberrypi.org (downloads.raspberrypi.org)|93.93.130.39|:443... connected.
HTTP request sent, awaiting response... 302 Found
Location: https://downloads.raspberrypi.org/raspbian/images/raspbian-2015-09-28/2015-09-24-raspbian-jessie.zip [following]
--2015-10-13 11:51:01--  https://downloads.raspberrypi.org/raspbian/images/raspbian-2015-09-28/2015-09-24-raspbian-jessie.zip
Reusing existing connection to downloads.raspberrypi.org:443.
HTTP request sent, awaiting response... 302 Found
Location: http://director.downloads.raspberrypi.org/raspbian/images/raspbian-2015-09-28/2015-09-24-raspbian-jessie.zip [following]
--2015-10-13 11:51:08--  http://director.downloads.raspberrypi.org/raspbian/images/raspbian-2015-09-28/2015-09-24-raspbian-jessie.zip
Resolving director.downloads.raspberrypi.org (director.downloads.raspberrypi.org)... 93.93.130.214, 93.93.128.211, 93.93.128.230, ...
Connecting to director.downloads.raspberrypi.org (director.downloads.raspberrypi.org)|93.93.130.214|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1332985725 (1.2G) [application/zip]
Saving to: `/dev/null'

 0% [                                                                                                             ] 3,321,176    644K/s  eta 35m 1s  ^C
pi@rpi ~ $
You could try to improve the signal received using an USB extension cable. The cable will help you to place the dongle in a place where the wifi signal is stronger than in the current position. This trick worked great here.
Attachments
USB-extension-cable.jpg
USB-extension-cable.jpg (36.14 KiB) Viewed 1447 times

lostcaggy
Posts: 7
Joined: Wed May 16, 2012 8:56 pm

Re: ssh slow using official wifi dongle

Thu Oct 22, 2015 3:41 pm

It's disappointing that the official wifi dongle is so slow. When a generic one in the same place is so much faster.

stderr
Posts: 2178
Joined: Sat Dec 01, 2012 11:29 pm

Re: ssh slow using official wifi dongle

Thu Oct 22, 2015 11:31 pm

I don't know if there are hardware or software issues with that dongle, but if you are using the wpa_supplicant, you can set it up to run in a terminal and constantly show what is going on. Basically, if you are having connection problems, it will alert you by going nuts.

It's possible, for example, that some software is negotiating a speed that is wrong for conditions and you end up with a ton of retries. You could watch for that.

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