Wi-Fi connection after update in Ubuntu

It is just a note that has helped me to resolve problem with Wi-Fi broken connection after system upgrade in Ubuntu 14.04 on a laptop DELL Inspiron 3537.

What: after system update Wi-Fi connecction does not work despite hardware Wi-Fi module is switched on (Wi-Fi connection LED is ON on the laptop) – transmission power is OFF.

$ iwconfig
eth0      no wireless extensions.

lo        no wireless extensions.

wlan0     IEEE 802.11bgn  ESSID:"FlatNetwork_2.4GHz"
          Mode:Managed  Frequency:2.462 GHz  Access Point: 10:FE:ED:FF:D2:AD
          ... ... ...

Transmission power is off (Tx-Power=off) as you can see it from the example above.

Solution: solution is pretty simple in my case, I have not dug why it may happen after system update, but it is enough (at least for me and for the considered problem) to down wlan0 network interface, then up it and reboot the system:

$ sudo ifdown -a
$ sudo ifup -a
$ sudo reboot 0



Screen brightness in Ubuntu

It is just a note that has helped me to resolve problem with brightness in Ubuntu 14.04 on laptop DELL Inspiron 3537.

What: screen brightness is not changed via system setting Brightness & Lock or using  Fn + F4 and Fn + F5.


  1. Check module that provides interface to control brightness:
    $ ls /sys/class/backlight
  2. Create configuration file for graphic card where brightness option will be specified.
    $ sudo touch /usr/share/X11/xorg.conf.d/20-intel.conf
    $ sudo nano /usr/share/X11/xorg.conf.d/20-intel.conf
  3. Create configuration to control brightness:
    Section "Device"
    	Identifier	"card0"
    	Driver		"intel"
    	Option		"Backlight"	"intel_backlight"
    	BusID		"PCI:0:2:0"
  4. Reboot laptop and check that screen brightness can be changed.