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I installed ubuntu 14.04 in my new laptop Lenovo Thinkpad E540
I connect to a wifi network but after a while I lost connection, I try to reconnect but it cann't connect again to any wifi netwotk. for connecting again i have to reboot computer.
here is part of my dmesg code:

[  618.444235] wlan0: authenticate with f8:1a:67:b5:da:63
[  618.464150] wlan0: send auth to f8:1a:67:b5:da:63 (try 1/3)
[  618.465700] wlan0: authenticated
[  618.467617] wlan0: associate with f8:1a:67:b5:da:63 (try 1/3)
[  618.471473] wlan0: RX AssocResp from f8:1a:67:b5:da:63 (capab=0x411 status=0 aid=2)
[  618.471683] wlan0: associated
[  618.471735] cfg80211: Calling CRDA for country: US
[  618.473575] cfg80211: Regulatory domain changed to country: US
[  618.473578] cfg80211:  DFS Master region: unset
[  618.473579] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
[  618.473581] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2700 mBm), (N/A)
[  618.473583] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 1700 mBm), (N/A)
[  618.473584] cfg80211:   (5250000 KHz - 5330000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (0 s)
[  618.473585] cfg80211:   (5490000 KHz - 5600000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (0 s)
[  618.473587] cfg80211:   (5650000 KHz - 5710000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (0 s)
[  618.473588] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 3000 mBm), (N/A)
[  618.473589] cfg80211:   (57240000 KHz - 63720000 KHz @ 2160000 KHz), (N/A, 4000 mBm), (N/A)
[  643.634049] wlan0: Connection to AP f8:1a:67:b5:da:63 lost
[  643.666952] cfg80211: Calling CRDA to update world regulatory domain
[  643.669050] cfg80211: World regulatory domain updated:
[  643.669053] cfg80211:  DFS Master region: unset
[  643.669054] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
[  643.669056] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[  643.669058] cfg80211:   (2457000 KHz - 2482000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[  643.669060] cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm), (N/A)
[  643.669061] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[  643.669062] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[  645.069564] wlan0: authenticate with f8:1a:67:b5:da:63
[  645.089661] wlan0: send auth to f8:1a:67:b5:da:63 (try 1/3)
[  645.091299] wlan0: authenticated
[  645.093193] wlan0: associate with f8:1a:67:b5:da:63 (try 1/3)
[  645.098035] wlan0: RX AssocResp from f8:1a:67:b5:da:63 (capab=0x411 status=0 aid=2)
[  645.098228] wlan0: associated
[  645.098291] cfg80211: Calling CRDA for country: US
[  645.100131] cfg80211: Regulatory domain changed to country: US
[  645.100133] cfg80211:  DFS Master region: unset
[  645.100134] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
[  645.100137] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300   mBi, 2700 mBm), (N/A)
[  645.100138] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 1700 mBm), (N/A)
[  645.100140] cfg80211:   (5250000 KHz - 5330000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (0 s)
[  645.100141] cfg80211:   (5490000 KHz - 5600000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (0 s)
[  645.100142] cfg80211:   (5650000 KHz - 5710000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (0 s)
[  645.100144] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 3000 mBm), (N/A)
[  645.100145] cfg80211:   (57240000 KHz - 63720000 KHz @ 2160000 KHz), (N/A, 4000 mBm), (N/A)
[  726.303619] wlan0: Connection to AP f8:1a:67:b5:da:63 lost
[  726.352482] cfg80211: Calling CRDA to update world regulatory domain
[  726.354514] cfg80211: World regulatory domain updated:
[  726.354517] cfg80211:  DFS Master region: unset
[  726.354518] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
[  726.354520] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[  726.354522] cfg80211:   (2457000 KHz - 2482000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[  726.354523] cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm), (N/A)
[  726.354524] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[  726.354526] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[  727.755050] wlan0: authenticate with f8:1a:67:b5:da:63
[  727.775175] wlan0: send auth to f8:1a:67:b5:da:63 (try 1/3)
[  727.776824] wlan0: authenticated
[  727.778713] wlan0: associate with f8:1a:67:b5:da:63 (try 1/3)
[  727.782440] wlan0: RX AssocResp from f8:1a:67:b5:da:63 (capab=0x411 status=0 aid=2)
[  727.782642] wlan0: associated
[  727.782693] cfg80211: Calling CRDA for country: US
[  727.784431] cfg80211: Regulatory domain changed to country: US
[  727.784433] cfg80211:  DFS Master region: unset
[  727.784434] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
[  727.784435] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2700 mBm), (N/A)
[  727.784437] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 1700 mBm), (N/A)
[  727.784438] cfg80211:   (5250000 KHz - 5330000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (0 s)
[  727.784439] cfg80211:   (5490000 KHz - 5600000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (0 s)
[  727.784439] cfg80211:   (5650000 KHz - 5710000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (0 s)
[  727.784440] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 3000 mBm), (N/A)
[  727.784441] cfg80211:   (57240000 KHz - 63720000 KHz @ 2160000 KHz), (N/A, 4000 mBm), (N/A)
[12208.927155] wlan0: deauthenticating from f8:1a:67:b5:da:63 by local choice (Reason: 3=DEAUTH_LEAVING)
[12218.549245] cfg80211: Calling CRDA to update world regulatory domain
[12218.551729] cfg80211: World regulatory domain updated:
[12218.551734] cfg80211:  DFS Master region: unset
[12218.551735] cfg80211:   (start_freq - end_freq @ bandwidth), (max_antenna_gain, max_eirp), (dfs_cac_time)
[12218.551738] cfg80211:   (2402000 KHz - 2472000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[12218.551741] cfg80211:   (2457000 KHz - 2482000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[12218.551743] cfg80211:   (2474000 KHz - 2494000 KHz @ 20000 KHz), (300 mBi, 2000 mBm), (N/A)
[12218.551745] cfg80211:   (5170000 KHz - 5250000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)
[12218.551746] cfg80211:   (5735000 KHz - 5835000 KHz @ 40000 KHz), (300 mBi, 2000 mBm), (N/A)

and also here is my iwconfig output:

eth0      no wireless extensions.

wlan0     IEEE 802.11bgn  ESSID:off/any  
          Mode:Managed  Access Point: Not-Associated   Tx-Power=20 dBm   
          Retry short limit:7   RTS thr=2347 B   Fragment thr:off
          Power Management:off

lo        no wireless extensions.

how can i fix it? i can just coonet to netwotk by wired connection now :(
can you please help me to fix it?

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1

3 Answers 3

Reset to default
2
+50

This problem has been reported many times. Some of the solutions are listed below.

Disable 802.11N

In the router : Change 802.11bgn to just 802.11bg.
In the driver : Depends on your WiFi card (but the above might be enough).

Encryption

Change the router WEP encryption to just WPA2 (CCMP)(AES) not (TKIP), if you have that option.

Router channel

Set the wireless channel in the router to 1 or 11, then save the router configuration and reboot it.

Disable IPV6

In Network Manager at top right corner of the screen, click on Edit connections -> Wireless tab, and set IPV6 to Ignore.

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6
  • Those are all pretty awful fixes don't ya think?
    – Peter Turner
    Oct 19, 2015 at 0:17
  • Only disabling 802.11N is detrimental - the others are harmless (to remark that for most uses 802.11g is quite enough). Another workaround is to replace the WiFi card with one that has a better driver for Ubuntu 14.04.
    – harrymc
    Oct 19, 2015 at 5:59
  • I've been looking this up pretty thoroughly, although I never came across any of these suggestions - I think the channel is probably the next step I'm going to take. For me at least, (and I don't know about the OP so much, the symptoms are the same) Syslog shows some problem with the connection being dropped because of the Government body the radio waves are associated with. It bombed out for me with two different nics (one integrated into the board and one usb nic that works just fine on a raspberry pi)
    – Peter Turner
    Oct 19, 2015 at 16:13
  • Channel 11 is supposed to be the strongest. I would also try disabling 802.11N, maybe slowing transmissions down may help. Check also the MTU size. Look at ethtool parameters. If the raspberry pi works fine, compare configs. That and the above is about the totality of my ideas.
    – harrymc
    Oct 19, 2015 at 17:42
  • 'nmcli c e {connection name}' then 'set connection.gateway-ping-timeout' to -1 (disabled) or a number above 300 ( this value is in seconds 300 == 5mins)
    – linuxdev2013
    Oct 21, 2015 at 13:04
0

Your log shows

deauthenticating from f8:1a:67:b5:da:63 by local choice (Reason: 3=DEAUTH_LEAVING)

This means your wireless software is deliberately choosing to disconnect from the access point. This is most likely a configuration issue or a software conflict on your client.

Suggestions include misconfigured supplicant software, or having multiple applications trying to manage the wireless at the same time:

https://bbs.archlinux.org/viewtopic.php?id=163575

Incorrect set CRDA data:

http://ubuntuforums.org/showthread.php?t=2259037

Or problematic drivers on Ubuntu 14.04:

http://ubuntuforums.org/showthread.php?t=2198221&page=3

However as you have not run the suggested wireless information script, it's hard to know. In particular, you've not specified what wireless card or driver is in use, but the last link refers to a Lenovo T440s which may have similar hardware.

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0

I saw a similar issue which turned out to be down to an old modprobe config file (in /etc/modprobe.d) I had installed a few years ago. Specifically it specified an option for the cfg80211 (WiFi stack module) options cfg80211 ieee80211_regdom="EU"

After commenting/removing the option and rebooting it was fixed. So check to see if any of your modprobe.d files contain config options for cfg80211 and try commenting/removing them.

Also it may help to check to see that the REGDOMAIN is set in /etc/default/crda. For more details see Linux Wireless Regulatory info.

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