Why does Ubuntu 12.10 wifi keep disconnecting?

Question

I am using Ubuntu 12.10 on a Macbook Pro with Broadcom BCM4331 wireless network card. I have installed the b43 driver in order to be able to use the wireless card. However, the wireless connection gets disconnected every few minutes (just randomly, sometimes after half an hour, sometimes after 10 or 15 minutes...).

I can see this in the network manager icon. And it reconnects automatically. This happens more when I am connected to WPA 2 and WPA2 enterprise, but also sometimes when I am connected to unsecured wireless networks too.

Please find the output of a number of command below. If you need more information please let me know. I appreciate any help in advance.

sudo ifconfig -a

lo        Link encap:Lokale Schleife  
      inet Adresse:127.0.0.1  Maske:255.0.0.0
      inet6-Adresse: ::1/128 Gültigkeitsbereich:Maschine
      UP LOOPBACK RUNNING  MTU:16436  Metrik:1
      RX packets:712 errors:0 dropped:0 overruns:0 frame:0
      TX packets:712 errors:0 dropped:0 overruns:0 carrier:0
      Kollisionen:0 Sendewarteschlangenlänge:0 
      RX-Bytes:56910 (56.9 KB)  TX-Bytes:56910 (56.9 KB)

wlan0     Link encap:Ethernet  Hardware Adresse 14:10:9f:db:d6:7b  
      inet Adresse:192.168.2.103  Bcast:192.168.2.255  Maske:255.255.255.0
      inet6-Adresse: fe80::1610:9fff:fedb:d67b/64 Gültigkeitsbereich:Verbindung
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metrik:1
      RX packets:411 errors:0 dropped:0 overruns:0 frame:0
      TX packets:468 errors:0 dropped:0 overruns:0 carrier:0
      Kollisionen:0 Sendewarteschlangenlänge:1000 
      RX-Bytes:119863 (119.8 KB)  TX-Bytes:81782 (81.7 KB)


lspci | grep Broadcom

03:00.0 Ethernet controller: Broadcom Corporation Device 16a3 (rev 10)
03:00.1 SD Host controller: Broadcom Corporation NetXtreme BCM57765 Memory Card Reader (rev 10)
04:00.0 Network controller: Broadcom Corporation BCM4331 802.11a/b/g/n (rev 02)

modprobe -l | grep b43

updates/cw-3.6/b43legacy.ko
updates/cw-3.6/b43.ko

modprobe -l | grep bcm

kernel/drivers/usb/host/bcma-hcd.ko
kernel/drivers/input/mouse/bcm5974.ko
kernel/drivers/media/dvb/frontends/bcm3510.ko
kernel/drivers/staging/bcm/bcm_wimax.ko
kernel/net/can/can-bcm.ko
updates/cw-3.6/bcma.ko
updates/cw-3.6/bcm203x.ko

cat /etc/network/interfaces
auto lo iface lo inet loopback

By the way, I don't know of this is odd or not, but, in the system log (/var/log/syslog) every few minutes I see authentication by wpa_supplicant like this:

NetworkManager[970]: <info> (wlan0): supplicant interface state: completed -> disconnected  
NetworkManager[970]: <info> (wlan0): supplicant interface state: disconnected -> scanning  
wpa_supplicant[1368]: wlan0: SME: Trying to authenticate with 20:2b:c1:50:0e:76 (SSID='foo' freq=2442 MHz)
[ 365.771706] wlan0: authenticate with 20:2b:c1:50:0e:76  
NetworkManager[970]: <info> (wlan0): supplicant interface state: scanning -> authenticating

Thanks for your reply. Here it is:# interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback — user140838, Mar 17 '13 at 12:31
By the way, I don't know of this is odd or not, but, in the system log (/var/log/syslog) every few minutes I see authentication by wpa_supplicant like this: NetworkManager[970]: (wlan0): supplicant interface state: completed -> disconnected NetworkManager[970]: (wlan0): supplicant interface state: disconnected -> scanning wpa_supplicant[1368]: wlan0: SME: Trying to authenticate with 20:2b:c1:50:0e:76 (SSID='foo' freq=2442 MHz) [ 365.771706] wlan0: authenticate with 20:2b:c1:50:0e:76 NetworkManager[970]: (wlan0): supplicant interface state: scanning -> authenticating — user140838, Mar 17 '13 at 12:39
I assume Ubuntu is not the only system on your laptop and that it is the only one where the problem occurs. this post on Ubuntu forums (http://ubuntuforums.org/showthread.php?t=1966236) deals with no wireless connection but perhaps can solve your issue. — catalesia, Mar 17 '13 at 16:00
Thanks for your follow up. Your assumption is true. However, I have already seen that page and tried it. But, no success! — user140838, Mar 18 '13 at 08:27
FYI: I found the same issue already reported on this page: http://askubuntu.com/questions/259469/cant-get-bcm4331-wireless-working-right — user140838, Mar 19 '13 at 09:29
This issue is not yet solved. Any help would be appreciated. — user140838, Mar 19 '13 at 09:30
Please select your own answer, when the system lets you, rather than changing the title to say "solved". :) — Thomas Ward, Mar 20 '13 at 18:09

score 2 · Accepted Answer · answered Mar 20 '13 at 18:06

2

I resolved my issue by installing Ubuntu 13.04 (daily build, 20. March). Now, I am writing this answer on Ubuntu 13.04. The wireless issue is solved completely. Other hardware is working perfectly fine.

answered Mar 20 '13 at 18:06

user140838

119

By the way, the wireless driver is installed by default and works out of the box. The driver is "wl" and not b43. – user140838 Mar 20 '13 at 18:09
The same answered to the same issue here: http://askubuntu.com/questions/259469/cant-get-bcm4331-wireless-working-right – user140838 Mar 21 '13 at 19:58

Why does Ubuntu 12.10 wifi keep disconnecting?

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