[Bug 602911] Re: Unstable WLAN connection on Dell Latitude E6500, BCM4322 802.11a/b/g/n, Ubuntu 10.04 x64

[Greg V]

Ok, I solved the problem at least for myself.

I am highly positive that in my case the issue lies within Apple Airport
Extreme-Ubuntu tandem. Laptop hardware has nothing to do with the
problem.

As you may know, the latest version of Apple Airport Extreme sports a
dual radio circuitry that allows it to broadcast in both, 2.4MHz and
5.8MHz bands.  It shows as b/g/n + a/n in Airport Manager.

I have the Airport set up in a bridge mode.  I also have MAC access
filter turned on.  The manager application has a setting for a 5MHz
network name, which by default is disabled.  This makes me to conclude
that by default, both radios broadcast the same SSID.

It seems that the same SSID broadcast at two frequencies confuse Ubuntu
and it only succeeds to connect if it chooses the same frequency,
failing if other frequency is picked up. Having an a/b/g/n network
adapter makes things the toughest as both frequencies are accessible to
a computer.

I should note that nor Windows, neither Mac OS X exhibit the same
problem, while both using a/b/g/n adapters, thus, seeing both
frequencies.

Here is what I did to solve the problem:
- Created a different network name for 5MHz band. It does not affect authentication/security policy you have set on Airport.
- In network-manager's wireless connection I specified MAC addresses in BSSID: and MAC address: fields. The first one tells Ubuntu which access point to connect to. Airport has a separate MAC address for each band, so I can explicitly tell what band to hook to.  The latter defines client's MAC address that is presented to access point.  Since I have MAC filtering enabled, I set this property to make sure things are straight.

With these changes I have not lost wireless connection even once during
the past week.  I am not saying all settings are necessary, most likely
setting a separate SSID would make the trick.

Now I am going to report a bug as I am sure things should work fine in
Ubuntu without these extra changes if they work fine in Windows and Mac
OS X.

Good luck!
Greg

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Unstable WLAN connection on Dell Latitude E6500, BCM4322 802.11a/b/g/n, Ubuntu 10.04 x64
https://bugs.launchpad.net/bugs/602911
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