Ubuntu 14.04 wifi problem

Oprava Acer Travelmate:

https://bbs.archlinux.org/viewtopic.php?id=134920

Step 0: Know your enemy
The problem I was dealing with was similar to the original poster’s and happened consistently. When my signal’s strength wasn’t good and the network card had lots of traffic (downloading a file while watching YouTube while …), the download speed would abruptly come to a halt. Removing and re-inserting the iwlwifi module would fix it temporarily, but later on it would relapse. Also, there was no apparent error to troubleshoot, since iwlwifi would print on dmesg only the re-connections and not any error.
The above was experienced with kernels 3.2, 3.5, 3.6, 3.7. I can’t say for sure that all versions of these kernels are problematic, so you are free to check it out your self. An easy way to check if patches were issued about iwlwifi in a specific kernel version can be found from here. Just compare the dates of the file changes between different kernel versions.
Also, you might want to know that the wifi was working seamlessly with the 3.3.8 version of the kernel. Thus, if you want to check out a different linux kernel, I’d suggest you start with this one. Obviously, this is for people using Debian or other distros that rely on older kernels. So, our first question would be…
Step 1: What is your kernel?
You can find a description of your system with this command:
uname -mor
My output is:
3.7.1-2-ARCH x86_64 GNU/Linux
Step 2: What is your hardware?
It is very important to know what your hardware is. If you have the same hardware as I do, then you probably have more chances to fix it. If you post a question in another forum and then mark your question as solved, people would like to know what your hardware was. If you send a bug report to the iwlwifi team, they will need your card’s model.
So, write:
lspci | grep -i net
My output is:
01:00.0 Network controller: Intel Corporation Centrino Wireless-N 130 (rev 34)
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 06)
Step 3: What is your problem?
You can see more debug info about your problem by writing:
dmseg
or to filter through these messages:
dmesg | grep iwlwifi
If you see any errors, tracebacks etc. then these are bugs and you’d best search for similar bugs here. If there are no similar bugs, I’d suggest you create a new bug report. The people that answer in this list are core developers of the iwlwifi module and you’d best send them these bug reports in order to help them track down these problems.
Step 4: Solution (?)
GRUB
The are many ways to disable IPv6. I did it using GRUB:
sudo cp /boot/grub/grub.cfg /boot/grub/grub.bak        #For backup reasons
sudo nano /etc/default/grub
Add this option „ipv6.disable=1“ to the line GRUB_CMDLINE_LINUX_DEFAULT=, so that your GRUB looks like this:
GRUB_DEFAULT=0                                                                  
GRUB_TIMEOUT=5                                                                  
GRUB_DISTRIBUTOR=“Arch“                                                         
GRUB_CMDLINE_LINUX_DEFAULT=“ipv6.disable=1″                                     
GRUB_CMDLINE_LINUX=““
.
.
.
Finally, do:
sudo grub-mkconfig -o /boot/grub/grub.cfg
sudo reboot
to update your grub and restart your laptop. If anything goes wrong, you can restore your grub.cfg file using the backup grub.bak we created above.
IWLWIFI OPTIONS
Provided IPv6 is disabled, you can check in real time which of the following options make a difference, without restarting your laptop:
sudo modprobe -r iwldvm iwlwifi
sudo modprobe iwlwifi 11n_disable=1 bt_coex_active=0 power_save=0  auto_agg=0 swcrypto=1
You can learn more about these options by writing:
modinfo iwlwifi
Hopefully, you will experience no disconnections from now on.
Now, in order to automatically pass these options at startup to iwlwifi, you can create a *.conf file inside /etc/modprobe.d directory.
nano /etc/modprobe.d/iwlwifi.conf
And add this line:
options iwlwifi 11n_disable=1 bt_coex_active=0 power_save=0 auto_agg=0 swcrypto=1
Step 5: This %@#%@ @#%#% doesn’t #%@#% work
Well, bummer. I’d highly recommend to inform the developers of iwlwifi about your problem, as I’ve mentioned above. If the dev list intimidates you, post about this problem here.
Good luck…
Edit
It’s likely that you may encounter the following strange behavior when trying to connect to your access point.
Copied form my dmesg:
[  904.190052] iwlwifi 0000:01:00.0: L1 Enabled; Disabling L0S
[  904.197452] iwlwifi 0000:01:00.0: Radio type=0x2-0x2-0x1
[  904.886420] wlan0: authenticate with 00:26:44:b3:16:a4
[  904.928370] wlan0: send auth to 00:26:44:b3:16:a4 (try 1/3)
[  904.930494] wlan0: authenticated
[  904.932220] wlan0: associate with 00:26:44:b3:16:a4 (try 1/3)
[  904.939798] wlan0: RX AssocResp from 00:26:44:b3:16:a4 (capab=0x411 status=0 aid=2)
[  904.942701] wlan0: associated
[  915.641048] wlan0: deauthenticating from 00:26:44:b3:16:a4 by local choice (reason=3)
If the above is coupled with the netcfg’s response:
> DHCP IP lease attempt failed.
                                                                          [FAILED]
then you have just encountered a strange dhcpcd bug, which has nothing to do with iwlwifi.

http://natalian.org/archives/2011/09/28/DHCP_IP_lease_attempt_failed_on_Archlinx/

 

============= Další postup ==========

iwconfig
eth0      no wireless extensions.

lo        no wireless extensions.

wlan0     IEEE 802.11abgn  ESSID:off/any  
          Mode:Managed  Access Point: Not-Associated   Tx-Power=15 dBm   
          Retry  long limit:7   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off

bad nameserver

 sudo echo -e „nameserver 8.8.8.8\n“ | sudo resolvconf -a wlan0

or

http://askubuntu.com/questions/368435/how-do-i-fix-dns-resolving-which-doesnt-work-after-upgrading-to-ubuntu-13-10-s

 3 down vote
    

I made the change suggested on the link below (disabling dnsmasq). Now everything works great! http://www.ubuntugeek.com/how-to-disable-dnsmasq-in-ubuntu-12-04precise.html

Open /etc/NetworkManager/NetworkManager.conf file.

sudo gedit /etc/NetworkManager/NetworkManager.conf

Comment out following line

dns=dnsmasq

to
# dns=dnsmasq

dát na lunux.net
http://www.ubuntugeek.com/how-to-disable-dnsmasq-in-ubuntu-12-04precise.html

==============

Atheros repair:
 

http://linuxg.net/fix-the-slow-connection-problem-when-using-wifi-on-ubuntu-13-04-12-04-or-linux-mint-13/
http://itsfoss.com/speed-up-slow-wifi-connection-ubuntu/

 

http://ubuntuforums.org/showthread.php?t=2238087

rfkill list all

Any improvement?

If not, let’s try another technique:
Code:

sudo modprobe -r ideapad-laptop
sudo rfkill unblock all
rfkill list all

sudo -i
echo „blacklist ideapad-laptop“  >>  /etc/modprobe.d/blacklist.conf
exit

Let’s see if there are any clues in the logs:
Code:

dmesg | grep -e wlan -e rtl

 Re: 14.04 Wireless internet connection not working, (Laptop Lenovo G40-30)

    First, check the settings in the router. WPA2-AES is preferred; not any WPA and WPA2 mixed mode and certainly not TKIP. Second, if your router is capable of N speeds, I have better luck with a channel width of 20 MHz in the 2.4 GHz band instead of automatic 20/40 MHz. I also have better luck with a fixed channel, either 1, 6 or 11, rather than automatic channel selection. After making these changes, reboot the router.

    Next, I recommend that your regulatory domain be set explicitly. Check yours:
    Code:

    sudo iw reg get

    If you get 00, that is a one-size-maybe-fits-all setting. Find yours here: http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2 Then set it temporarily:
    Code:

    sudo iw reg set IS

    Of course, substitute your country code if not Iceland. Set it permanently:
    Code:

    gksudo gedit /etc/default/crda

    Use nano or kate or leafpad if you don’t have the text editor gedit.

    Change the last line to read:
    Code:

    REGDOMAIN=IS

    Proofread carefully, save and close the text editor.

    Next, I’d set IPv6 to Ignore in Network Manager: http://docs.fedoraproject.org/en-US/…pv6-ignore.png This example is for ethernet, but you want wireless.

    If these changes do not help, please try:
    Code:

    sudo modprobe -r rtl8723be
    sudo modprobe rtl8723be swenc=1

    If it helps, make it permanent:
    Code:

    sudo -i
    echo „options rtl8723be swenc=1“  >>  /etc/modprobe.d/rtl8723be.conf
    exit

————

 

http://ubuntuforums.org/showthread.php?t=2197316

    Please get a temporary wired ethernet connection and do:

    Code:

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

    I suggest you download this to your desktop: https://www.kernel.org/pub/linux/ker…12.2-1.tar.bz2 Right-click it and select ‚Extract Here.‘ Now open a terminal and do:

    Code:

    cd ~/Desktop/backports-3.12.2-1/
    make defconfig-ath9k
    make
    sudo make install
    sudo modprobe -r ath9k && sudo modprobe ath9k

    Your wireless should now be working. You will have compiled the driver for your currently running kernel only. When Update Manager installs a later linux-image, after reboot, re-compile:

    Code:

    cd ~/Desktop/backports-3.12.2-1/
    make clean
    make defconfig-ath9k
    make
    sudo make install
    sudo modprobe -r ath9k && sudo modprobe ath9k

    Post back if you get stuck.

Ubuntu 14.04 wifi problem