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I have looked through all the previous questions but turning power management off for the Wi-Fi card didn't work. This problem seems to be with the Lenovo Thinkpads. I switched to Ubuntu 11.10 from Windows 7 3 days ago so I'm new to the operating system.

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got the same problem - a terribly slow wireless connection - on a thinkpad e420s. you'll probably have the same issue I have with the intel centrino card; type sudo lspci -nn in a terminal and see "network controller". if you've got this card, see the bugreport here: bugs.launchpad.net/ubuntu/+source/linux/+bug/836250 – eskararriba Apr 9 '12 at 6:34
    
good post, can you tell me what the instructions actually doing? are these instructions for a specific wireless card? if you made your answer a bit more specific you can post the answer to your own question and accept it :) – amc May 3 '12 at 3:32
    
Have you solved this question? – pl1nk Jun 24 '12 at 23:11
    
I don't understand why no one here bothers to explain what all these commands actually do? Posting instructions like "on ubuntu x.xx copy this code into a terminal" is not helpful at all, isn't it? If you cannot provide an explanation please don't answer. – jan groth Aug 20 '13 at 2:32
    
This looks like a starting point to understand most answers. No Intel wifi -> no result. – jan groth Aug 20 '13 at 2:39

OP Posted:

  • Note1: The slow connection can be due to your service provider or any other reason, to check it, try the same network by any other computer with different OS or by connection to the network by a cable. If it is fast, this solution can help you. If not, it can be wasting of time!*

  • Note2: In the first link in the References I put, there are more methods to solve the slow wireless connection. Each method solves different possible reason of the slow connection. I recommend to test the solution I put here before searching for different methods because it is most probably effective.*


If you are using Ubuntu 11.10, do the following:

open terminal. Type the following two lines:

sudo rmmod -f iwlagn
sudo modprobe iwlagn 11n_disable=1

Now, check your wireless Internet speed. If it is still slow, this solution is probably not a solution for your case. In this case, just restart the computer to revert the change you did. If it becomes normal and fast, do it permanently by typing the following line in the terminal:

gksudo gedit /etc/modprobe.d/iwlagn-disable11n.conf

A file will be opened. At the end of the file, paste the following line then save:

options iwlagn 11n_disable=1

After saving, just quit, and ENJOY!


Solution for Ubuntu 12.04:

open terminal. Type the following two lines:

sudo rmmod iwlwifi
sudo modprobe iwlwifi 11n_disable=1

Now, check your wireless Internet speed. If it is still slow, this solution is probably not a solution for your case. In this case, just restart the computer to revert the change you did. If it becomes normal and fast, do it permanently by typing the following line in the terminal:

gksudo gedit /etc/modprobe.d/iwlwifi-disable11n.conf

A file will be opened. At the end of the file, paste the following line then save:

options iwlwifi 11n_disable=1

After saving, just quit, and ENJOY!


References:

*I tried both solutions and they work.

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I have to note that this solution works for shared wifi connection too. I had uplink speed about 2Mbits, but shared wifi as slow as 40kbits. Doing this on both machines did work. (probably the leecher machine was to blame) – culebrón Feb 1 '14 at 4:13
1  
Valid still for 14.10. If you receive "ERROR: Module iwlwifi is in use by: iwlmvm", use "sudo rmmod iwlmvm" – Turtles Are Cute Apr 13 '15 at 17:15

I solved this for myself by using the instructions here.

in a terminal, write:

echo "options iwlagn 11n_disable=1" | sudo tee /etc/modprobe.d/iwlagn.conf
sudo modprobe -rfv iwlagn
sudo modprobe iwlagn

For 12.04 and newer: change options iwlagn 11n_disable=1 to options iwlwifi 11n_disable=1

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I dont know what this does but it works. you are brilliant, thank you! – Kaine McAliece Apr 21 '12 at 3:34
    
Had to restart for it to work and then it's perfect! – miguelv May 3 '12 at 22:28
    
I don't have a iwlagn.conf in modeprobe.d, should I create one? btw I'm using 12.04 – shengy Oct 10 '12 at 12:52
    
"For 12.04, change options iwlagn 11n_disable=1 to options iwlwifi 11n_disable=1" - ok, but should we still edit iwlagn.conf or iwlwifi.conf ? – sylvainulg Apr 16 '13 at 7:22
2  
For the record, that disables the "n" flavour of the 802.11 (aka WiFi) protocol, which is buggy on intel chipsets. Check the output of "iwconfig wlan0" before and after issueing those commands. It should start with "IEEE 802.11abgn" before and just "802.11abg" after. – sylvainulg Apr 16 '13 at 7:24

For 12.04, change:

options iwlagn 11n_disable=1

To:

options iwlwifi 11n_disable=1
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This bug affects my laptop with Centrino Ultimate-N 6300 as well. The only thing that helped was turning on the swcrypto parameter. My /etc/modprobe.d/iwlwifi.conf now looks like this:

options iwlwifi 11n_disable=1 led_mode=1 swcrypto=1

And I can use wifi without problems. However, the fact that n-networks can not be used remains annoying.

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Has this been corrected in Ubuntu 15 yet? – Jonathan Leaders Apr 27 '15 at 23:48

These commands helped and worked for me, Kubuntu 15.10 (wily), My Intel Wifi Adapter (Intel Corporation Centrino Wireless-N 1000) went to mostly full speed from a crawl (snail speed):

su

echo options iwlwifi 11n_disable=1 | sudo tee /etc/modprobe.d/iwlagn.conf

echo options iwlwifi 11n_disable=1 | sudo tee /etc/modprobe.d/iwlwifi.conf

sudo modprobe -rfv iwlwifi

sudo modprobe iwlwifi

apt-get update

I had so much difficulty at first to find this, I hope it helps someone out there, it was so slow at first, when I installed Linux (Kubuntu), it was driving me crazy :)

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My wifi cutout again and I did more research to find out that you can edit the line to: options iwlwifi 11n_disable=1 bt_coex_active=0 power_save=0 auto_agg=0 swcrypto=1 – David V. Nov 7 '15 at 5:34
    
I made a text file in my documents folder named iwlwifi.conf and added the original commands and the added line mentioned in the previous comment to read: # /etc/modprobe.d/iwlwifi.conf # iwlwifi will dyamically load either iwldvm or iwlmvm depending on the # microcode file installed on the system. When removing iwlwifi, first # remove the iwl?vm module and then iwlwifi. remove iwlwifi \ (/sbin/lsmod | grep -o -e ^iwlmvm -e ^iwldvm -e ^iwlwifi | xargs /sbin/rmmod) \ && /sbin/modprobe -r mac80211 options iwlwifi 11n_disable=1 bt_coex_active=0 power_save=0 auto_agg=0 swcrypto=1 – David V. Nov 7 '15 at 5:42
    
Then save the document and run konsole and enter the commands su cp /home/[replaceyourusernamehere]/Documents/iwlwifi.conf /etc/modprobe.d/iwlwifi.conf After that my wifi started to work faster than before when I just entered: options iwlwifi 11n_disable=1 – David V. Nov 7 '15 at 5:44
    
****I DID NOT DO THIS PART BELOW BUT IT MAY WORK**** You may need to still possibly run the commands as: su echo options options iwlwifi 11n_disable=1 bt_coex_active=0 power_save=0 auto_agg=0 swcrypto=1 | sudo tee /etc/modprobe.d/iwlwifi.conf sudo modprobe -rfv iwlwifi sudo modprobe iwlwifi apt-get update I was still getting error module iwlwifi was in use when I previously ran: sudo modprobe -rfv iwlwifi. Let me know if this works for you or not in the comments. – David V. Nov 7 '15 at 5:45

I followed the last instructions in this post.

It solved the issue on my Shuttle XS35 (Atom D510) with Ubuntu 12.04 from a starving speed of 0,91 Mbps to 8,74 Mbps (9x quicker).

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Open a terminal (alt+ctrl+t) type: sudo rmmod -f iwlwifi

Then type: sudo modprobe iwlwifi 11n_disable=1

Now check if the speeds have improved. If yes lets make it permanent.

Type gksudo gedit /etc/modprobe.d/iwlwifi_disable11n.conf

Add the following line to the end of the file:

options iwlwifi 11n_disable=1

After that, save it and quit!

In case you get an error like this:

ERROR: Removing 'iwlwifi': No such file or directory

replace iwlwifi with iwlagn in the above commands and try again.

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UPDATE: It somehow ended up not connecting again so i did more research here is what i found: Restore the original iwlwifi commands in the file iwlwif.conf (may not be necessary to restore the original commands in the iwlwifi.conf file) in /etc/modprobe.d/iwlwifi.conf and pasted this line at the end:

options iwlwifi 11n_disable=1 bt_coex_active=0 power_save=0 auto_agg=0 swcrypto=1

To restore the file you can make a new text file in your documents named iwlwifi.conf and add the command lines:

# /etc/modprobe.d/iwlwifi.conf
# iwlwifi will dyamically load either iwldvm or iwlmvm depending on the
# microcode file installed on the system.  When removing iwlwifi, first
# remove the iwl?vm module and then iwlwifi.
remove iwlwifi \
(/sbin/lsmod | grep -o -e ^iwlmvm -e ^iwldvm -e ^iwlwifi | xargs /sbin/rmmod) \
&& /sbin/modprobe -r mac80211

options iwlwifi 11n_disable=1 bt_coex_active=0 power_save=0 auto_agg=0 swcrypto=1

Then save the document and run konsole and enter the commands

su 

cp /home/[replaceyourusernamehere]/Documents/iwlwifi.conf /etc/modprobe.d/iwlwifi.conf

After that my wifi started to work faster than before when I just entered:

options iwlwifi 11n_disable=1

****NOTE: THE ABOVE JUST WORKED FOR ME WHERE I COPIED THE FILE USING SUPERUSER**** ****I DID NOT DO THIS PART BELOW BUT IT MAY or MAY NOT WORK****

You may need to still possibly run the commands as:

su

echo options options iwlwifi 11n_disable=1 bt_coex_active=0 power_save=0 auto_agg=0 swcrypto=1 | sudo tee /etc/modprobe.d/iwlwifi.conf

sudo modprobe -rfv iwlwifi

sudo modprobe iwlwifi

apt-get update

I was still getting error module iwlwifi was in use when I previously ran:

sudo modprobe -rfv iwlwifi.

Let me know if this works for you or not in the comments.

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To become superuser you need to run command: sudo passwd root – David V. Nov 7 '15 at 6:07

I ended up having to redo my wireless network instead. My network had 2.4Ghz and 5Ghz using the same SSID. When I split those up and connected to the 2.4Ghz network the speed issues disappeared. Since the 5Ghz network doesn't show, I'm assuming my card must not support 5Ghz and it must have been trying to connect to it sometimes.

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1  
Sorry, but in what way this solve OP's problem? – Braiam Aug 30 '13 at 2:17

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