I have just installed Ubuntu 14.04 on my machine. My kernel version is:


My problem is that download speed in Ubuntu (measured via speedtest.net) is 0.78 Mbps while on Windows (installed on the same machine) I have 21,84 Mbps. What can be important is that I also had a problem with constantly disconnecting Wi-Fi, which I resolved by forcing AES encryption in my Wi-Fi router. My Wi-Fi adapter is

D-Link DWA-121 Wireless N 150 Pico USB Adapter

and the relevant part of output of iwconfig is:

wlan0     IEEE 802.11bgn  ESSID:"UPC1307036"  
          Mode:Managed  Frequency:2.412 GHz  Access Point: 64:7C:34:3D:ED:CE   
          Bit Rate=72.2 Mb/s   Tx-Power=20 dBm   
          Retry short limit:7   RTS thr=2347 B   Fragment thr:off
          Power Management:off
          Link Quality=62/70  Signal level=-48 dBm  
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:134   Missed beacon:0

I tried the solutions from other questions of this kind, but they didn't work, so I'm starting a new question.

  • I hope my question is worded properly. Please let me know if it lacks some important informations. – Marek Lipka Apr 29 '15 at 19:47

Compile and install the proprietary Realtek 8192cu driver. To do this, run the following commands in an open terminal:

sudo apt-get update && sudo apt-get install git build-essential linux-headers-generic dkms
git clone https://github.com/dz0ny/rt8192cu.git --depth 1
cd rt8192cu
sudo make dkms

For hard installation use:

sudo make install

instead of sudo make dkms .

To enable this driver, use the command:

sudo modprobe 8192cu

Finally, update /etc/modules with this command before you reboot:

echo '8192cu' | sudo tee -a /etc/modules

Source: github.com/dz0ny

Also: https://askubuntu.com/a/395826/167115

  • Unfortunately, no luck. sudo modprobe 8192cu command gives the error: modprobe: ERROR: could not insert '8192cu': Device or resource busy. – Marek Lipka Apr 29 '15 at 20:11
  • 1
    Ok, it's because I had probably trail of attemption of solving this (or previous) issue in my /etc/modules. After I cleaned this file and rebooted the system, everything works properly. So thank you very much for your time and I finally have the opportunity to accept the answer after long presence on StackExchange. :) – Marek Lipka Apr 29 '15 at 20:18
  • Also, hard installation is not recommended and the DKMS method is preferred as the DKMS method will automatically install with a new kernel update whereas a hard install will require the driver be reinstalled each time a new kernel is installed. – mchid Apr 29 '15 at 23:28

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