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I've just updated Ubuntu from 10.04 to 12.04. But after update i am unable to connect to my home wifi router. I've tried connecting it with my Android device, it works fine. Sometimes it connects to my home wifi but no internet is available.

Device configuration is below:

saquib@saquib-laptop:~$ ifconfig
eth0      Link encap:Ethernet  HWaddr e8:11:32:20:de:7a  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:41 Base address:0xc000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:3453 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3453 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:271550 (271.5 KB)  TX bytes:271550 (271.5 KB)

wlan0     Link encap:Ethernet  HWaddr 08:10:76:c5:2b:d2  
          inet6 addr: fe80::a10:76ff:fec5:2bd2/64 Scope:Link
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:37 errors:0 dropped:0 overruns:0 frame:0
          TX packets:268 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:5276 (5.2 KB)  TX bytes:32395 (32.3 KB)

saquib@saquib-laptop:~$ iwconfig
lo        no wireless extensions.

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

eth0      no wireless extensions.

saquib@saquib-laptop:~$ rfkill list
0: hci0: Bluetooth
    Soft blocked: no
    Hard blocked: no
1: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: no

saquib@saquib-laptop:~$ sudo lshw -C network
  *-network               
       description: Ethernet interface
       product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:04:00.0
       logical name: eth0
       version: 06
       serial: e8:11:32:20:de:7a
       size: 10Mbit/s
       capacity: 1Gbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=half firmware=rtl_nic/rtl8168e-2.fw latency=0 link=no multicast=yes port=MII speed=10Mbit/s
       resources: irq:41 ioport:3000(size=256) memory:fc900000-fc900fff memory:fca04000-fca07fff
  *-network
       description: Wireless interface
       physical id: 4
       bus info: usb@2:1.2
       logical name: wlan0
       serial: 08:10:76:c5:2b:d2
       capabilities: ethernet physical wireless
       configuration: broadcast=yes driver=rtl8192cu driverversion=3.2.0-54-generic firmware=N/A link=no multicast=yes wireless=IEEE 802.11bgn


saquib@saquib-laptop:~$ lspci
00:00.0 Host bridge: Intel Corporation Core Processor DRAM Controller (rev 02)
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02)
00:16.0 Communication controller: Intel Corporation 5 Series/3400 Series Chipset HECI Controller (rev 06)
00:1a.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 05)
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio (rev 05)
00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 1 (rev 05)
00:1c.3 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 4 (rev 05)
00:1d.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 05)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev a5)
00:1f.0 ISA bridge: Intel Corporation Mobile 5 Series Chipset LPC Interface Controller (rev 05)
00:1f.2 SATA controller: Intel Corporation 5 Series/3400 Series Chipset 4 port SATA AHCI Controller (rev 05)
00:1f.3 SMBus: Intel Corporation 5 Series/3400 Series Chipset SMBus Controller (rev 05)
00:1f.6 Signal processing controller: Intel Corporation 5 Series/3400 Series Chipset Thermal Subsystem (rev 05)
04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 06)
3f:00.0 Host bridge: Intel Corporation Core Processor QuickPath Architecture Generic Non-core Registers (rev 02)
3f:00.1 Host bridge: Intel Corporation Core Processor QuickPath Architecture System Address Decoder (rev 02)
3f:02.0 Host bridge: Intel Corporation Core Processor QPI Link 0 (rev 02)
3f:02.1 Host bridge: Intel Corporation Core Processor QPI Physical 0 (rev 02)
3f:02.2 Host bridge: Intel Corporation Core Processor Reserved (rev 02)
3f:02.3 Host bridge: Intel Corporation Core Processor Reserved (rev 02)


saquib@saquib-laptop:~$ nm-tool 

NetworkManager Tool

State: disconnected

- Device: wlan0 ----------------------------------------------------------------
  Type:              802.11 WiFi
  Driver:            rtl8192cu
  State:             disconnected
  Default:           no
  HW Address:        08:10:76:C5:2B:D2

  Capabilities:

  Wireless Properties
    WEP Encryption:  yes
    WPA Encryption:  yes
    WPA2 Encryption: yes

  Wireless Access Points 
    TP-LINK_E86B12:  Infra, A0:F3:C1:E8:6B:12, Freq 2417 MHz, Rate 54 Mb/s, Strength 99 WPA WPA2


- Device: eth0 -----------------------------------------------------------------
  Type:              Wired
  Driver:            r8169
  State:             unavailable
  Default:           no
  HW Address:        E8:11:32:20:DE:7A

  Capabilities:
    Carrier Detect:  yes

  Wired Properties
    Carrier:         off
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1 Answer 1

First of all, ensure you have the necessary prerequisites:

sudo apt-get install linux-headers-generic build-essential dkms git

Clone the updated driver with git:

git clone https://github.com/pvaret/rtl8192cu-fixes.git

Set it up as a DKMS module:

sudo dkms add ./rtl8192cu-fixes

Build and install the driver:

sudo dkms install 8192cu/1.8

Refresh the module list:

sudo depmod -a

Ensure the native (and broken) kernel driver is blacklisted:

sudo cp ./rtl8192cu-fixes/blacklist-native-rtl8192.conf /etc/modprobe.d/

Let's not take any chances. Instruct Ubuntu to load the new driver when it starts up.

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

Reboot.

You're done.

Thanks to P. Varet for this awesome fix.

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Please do not post duplicate answers on different questions. It just creates more work for the moderators. If the questions are so similar that the same answer works on each, then the later of the two is likely a duplicate and should be flagged as such. –  RolandiXor Dec 25 '13 at 6:26

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