I'm also getting this periodic loss of connection problem. I've had it
with 10.04, 11.10 and now 12.04 but it is much much worse on 12.04.
Dell Latitude E6400 with a Broadcom chipset wireless card (I think it was a
BCM4312)
Dell Latitude E6420 with both a Broadcom (BCM43228) and Intel (AGN5300) chipset
wireless card
On the first laptop (E6400) when I was running 10.04 the problem
resulted in sluggish response when using SSH or browsing. I was getting
about 2% one-way packet loss (i.e. pinging out from the laptop to the
WAP showed packet loss, but pinging from another machine to the laptop
showed no lost packets.) When first booted the network was fine but
would deteriorate over a period of about 60 minutes.
On the same laptop using Ubuntu 11.10 the problem became worse with
frequent disconnects. Only rebooting the laptop would reconnect the
wireless.
Again, on the same laptop with 12.04 the wireless was completely
unusable. It would associate with the WAP and could send and receive a
few hundred packets before reporting any host I tried to ping as
unreachable. With all three versions of Ubuntu on this laptop I only
experienced the problem at home and not at work so put it down to my WAP
at home being incompatible with the laptop's wireless card.
On the second laptop (E6420) I've only ever tried Ubuntu 12.04. With the
Broadcom wireless card I found that, at home, it would work for a couple
of hours then either drop the connection completely or suffer from heavy
packet loss (>20%). At work it would appear to be associated with the
WAP but trying to ping another machine would result in "network
unreachable" messages. Routing tables were all correct.
I then tried an Intel AGN5300 wireless card in the same laptop. It is
better but I see more or less the same symptoms: at home I get
disconnections or high packet loss after a couple of hours use; at work
I see the wireless is associated with a WAP but get "network
unreachable" when pinging, or high packet loss. I also get wildly
varying connection bit-rates and excessively high "Invalid misc" count
from iwconfig. This was reported just five minutes after rebooting:
iwconfig wlan0
wlan0 IEEE 802.11abg ESSID:"Linguamatics"
Mode:Managed Frequency:2.412 GHz Access Point: F8:D1:11:50:C9:4C
Bit Rate=48 Mb/s Tx-Power=15 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:off
Link Quality=70/70 Signal level=-31 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:15 Invalid misc:125154 Missed beacon:0
I'm currently running iwlwifi with the following options:
swcrypto=1 11n_disable=1 power_save=0
which helps a lot but doesn't completely remove the problem.
The fact that I've had similar problems with two laptops, two different
WAPs, and three different chipset wireless cards seems to suggest this
problem is not a fault with the hardware or drivers but something in
Ubuntu itself.
Note that I do not have access to the first laptop any more but I do
still have both wireless cards for the new one. I will also try the
latest kernel but this may take a while as this is a work laptop and I'm
on-call until late next week so can't really be dicking about with it
too much.
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https://bugs.launchpad.net/bugs/984552
Title:
[8086:0085] iwlwifi intermittently losing connectivity
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