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[Brian Murray <brian@xxxxxxxxxx>]

** Tags added: trusty

** Package changed: ubuntu => linux (Ubuntu)

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https://bugs.launchpad.net/bugs/1331860

Title:
  wireless lags

Status in “linux” package in Ubuntu:
  New

Bug description:
  Hi,

  i already discussed the following issue already in the german forum
  http://forum.ubuntuusers.de/topic/netzwerk-lags-nach-kernel-update-3-13-14-04-lt/
  and in your Official Ubuntu IRC Support Channel, without a solution.

  System:
  new Ubuntu: 14.04 LTS
  new Kernel: 3.13.0-29-generic
  old Ubuntu: 13.10
  old Kernel: 3.11.0-19-generic

  wireless device: TP-LINK WND4800, Atheros chipset
  wireless driver: ath9k
  wireless operating mode: 2.4ghz @ 802.11bgn and 5ghz @ 802.11a+n
  wireless router: fritz!box 3390

  Before upgrading to Ubuntu 14.04 LTS everything worked fine.
  After upgrading to Ubuntu 14.04 LTS the wireless connection produced sequently lags, when sending a ping to my wireless router.
  The lag sequence duration is around 5 seconds, the duration to the next lag sequence is around 100 seconds.
  Each ping get a reply (no requests get lost), but the delay of the reply raises up to 2000 miliseconds. 
  Normally the ping is around 1 or 2 miliseconds.
  I can reproduce this behavior manually by running 'sudo iwlist wlan1 scan' and keep watching the ping in another terminal window.
  I also used 'iwevent' to watch on events fired by the wireless interface while the lag is happening:
  '01:31:13.289166   wlan1    Scan request completed' is the only message i get.

  When booting the 3.11 kernel everything works fine again, no lags occur.
  If i try to reproduce the behavior with a manual scan as described before, no lags occur, everything keeps working fine.

  I already tried several configurations using special driver options like "nohwcrypt" and "debug", but dmesg and syslog do not log any failures or warnings.
  If i downgrade the wireless router to 2.4ghz @ 802.11b+g (54mbit) the new kernel (3.13) has also no failed pings and no massive lags, but this is not a stable solution for me due to many other wireless networks in my environment.

  So i assume there has been something changed between the kernel 3.11 and 3.13 or the belonging ath9k driver.
  I thought about the wireless scanning interval of the network manager, but i think changing this would also be just a workaround than a clean solution.

  Any ideas or recommendations how to solve this or how to collect more
  relevant information about this issue?

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