Hi,
I use a HP EliteBook equipped with an Intel Centrino Advanced-N 6205
network adapter, it uses the iwlwifi module, on Ubuntu 12.04.
I often cannot connect to my wireless network. Other computers
connect without problems. It is not reproducible, but it occurs, say
once per week. If it doesn't connect, nothing helps, not even a
reboot. I find the following messages in my syslog:
Aug 6 15:34:49 dejon NetworkManager[1042]: <warn> (wlan0): DHCPv4 request
timed out.
The more detailed syslog is attached. DHCP works for all other
computers. If I connect this computer via cable it also works
without problems. So it seems to be related to this particular
computer and its wireless configuration. But I have no clue how to
investigate further.
Any ideas what might be the cause?
Marco
On Mon, 2012-08-06 at 16:14 +0200, Marco wrote:
> Hi,
>
> I use a HP EliteBook equipped with an Intel Centrino Advanced-N 6205
> network adapter, it uses the iwlwifi module, on Ubuntu 12.04.
>
> I often cannot connect to my wireless network. Other computers
> connect without problems. It is not reproducible, but it occurs, say
> once per week. If it doesn't connect, nothing helps, not even a
> reboot. I find the following messages in my syslog:
>
> Aug 6 15:34:49 dejon NetworkManager[1042]: <warn> (wlan0): DHCPv4 request
> timed out.
>
> The more detailed syslog is attached. DHCP works for all other
> computers. If I connect this computer via cable it also works
> without problems. So it seems to be related to this particular
> computer and its wireless configuration. But I have no clue how to
> investigate further.
>
> Any ideas what might be the cause?
What kernel version? Is the network an 802.11n-enabled network? If you
have kernel version 3.2, try to disable 802.11n and see if that makes
things happier. I've had a number of iwlwifi bug reports with the 3.2
kernel from 12.04 that seem to be 802.11n related. Association happens
correctly, but data frames do not work.
Do something like the following:
rmmod iwlwifi
modprobe iwlwifi 11n_disable=1
(let it reconnect)
If that works, it can be made more permanent by using modprobe config
files to set the module options whenever it's loaded. Or, better yet,
upgrade your kernel version to 3.4 or later, but that's probably not
something that Canonical will do in the near future with 12.04.
Dan
On 2012-08-06 Dan Williams <[email protected]>
wrote:
> What kernel version?
3.2.0
> Is the network an 802.11n-enabled network?
Nope.
> If you have kernel version 3.2, try to disable 802.11n and see if
> that makes things happier.
Unfortunately not.
> Association happens correctly, but data frames do not work.
Sorry, I don't quite get it. What is the problem here (if you can
tell), a bug in the driver?
> Do something like the following:
>
> rmmod iwlwifi
> modprobe iwlwifi 11n_disable=1
> (let it reconnect)
Same as before.
> Or, better yet, upgrade your kernel version to 3.4 or later, but
> that's probably not something that Canonical will do in the near
> future with 12.04.
If it helps, I can build and install my own kernel. What would you
suggest, any objections against 3.5.0 or should I go for a 3.4.0?
Thanks for your help.
Marco
On 2012-08-06 Dan Williams <[email protected]>
wrote:
Hi,
I am sorry do wake up this old thread again (should I start a new
one instead?).
> Ok, that does all look fine. At this point, either the wifi driver
> isn't cooperating, or there isn't a DHCP server listening.
I managed to find another USB network adapter with a different
chipset which works perfectly. My guess is that the DHCP works (I
don't have access to the DHCP server), since it works fine for all
other hosts on the network.
> I'd rule out the firewall because typically they let DHCPv4
> through by default. One other thing you could do is set the
> connection to "manual" (ie, static) IPv4 addressing, enter an
> address that you know is on the router's subnet, and try to ping
> the default router. If that works, then clearly something is
> wrong with DHCP.
The ping did not succeed.
> If that doesn't work and you're sure the address/netmask you set
> is correct, then there's something wrong in the driver.
I am not 100% sure that the values I input were correct. I used the
same settings that a different host used and picked a random IP
address on the same subnet.
That way I am connected to the network, but don't have internet
access (e.g. cannot ping google by IP address).
> Yet another alternative is to do the static IP thing and then
> run a wireshark packet capture and see if the wifi card sees any traffic
> at all.
I did that and wireshark receives packages. But I don't really know
what to look for, to be honest. I can provide a wireshark capture
file, if necessary. But I guess it makes more sense to send it via
email, instead of dropping a big binary blob in this list.
> Anyone else have any thoughts? If the 4-way handshake works, that
> indicates your WPA passphrase is correct.
It is definitely correct. As I said, if I use a different adapter on
the same computer with the same settings assigned via DHCP it works.
Marco