How to Fix Slow Wireless with Intel 4965 AGN


Possible Duplicate:
Slow wireless with an Intel 4965

We run Ubuntu 12.04, 32bit, with the current kernel 3.2.27-generic on an MSI EX700.

I've already added the 11n_disable=1 tweek, without whcih, wireless has been unusable.

Now, it works OK, but speedtest shows:

Windows XP - down 11.68mbps, up 2.07mbps

Ubuntu 12.04 - down 2.06mbps up 2.0mbps

We've disabled ipv6, tried static and dinamic IPs, tried both swcrypto=0 and swcrypto=1 options, none of whcih made any difference.

The problem may be the symptom of high packet loss. For example, here's the output of iwconfig after booting and testing the speeds:

wlan0     IEEE 802.11abg  ESSID:"amu"  
      Mode:Managed  Frequency:2.462 GHz  Access Point: 00:78:9E:FA:32:C8   
      Bit Rate=54 Mb/s   Tx-Power=15 dBm   
      Retry  long limit:7   RTS thr:off   Fragment thr:off
      Encryption key:off
      Power Management:off
      Link Quality=58/70  Signal level=-52 dBm  
      Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
      Tx excessive retries:11  Invalid misc:3627   Missed beacon:0

I've posted a help request before with lots of technical info and outputs.

Best Answer

(answer in progress)

The iwl4965/iwlegacy driver has had a number of regressions in the past, but they've usually been fixed.

The high invalid misc number may be related to your low throughput.

Please try/test/answer a couple of things, and ask me for a howto when needed:

  1. Do you experience this problem with the Ubuntu 12.04 Desktop Live CD (which runs kernel 3.2.0-23, IIRC)?
  2. Can you try using wicd instead of NetworkManager?
  3. Can you compile and try the latest iwl4965 driver from the compat-wireless tree?
  4. What is the manufacturer/model number of your router?
  5. Does your laptop have bluetooth?
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