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Sporadic disconnects when 802.11n is enabled in clients

Hello Guys

I am desperately in need for some help. Recently I upgraded the wireless infrastructure in my campus and deployed WISM2 controllers and Cisco 3502i APs throughout the campus. Until now all my users were using 802.11b/g/a speeds without any issues. However, now I am trying to enable 802.11n speeds in a test group of users by enabling AES encryption and I am seeing lot of issues. These test users sporadically loose wifi connection and an asterix appears in the WIFI icon in the task bar. Interesting part is that all the manually configured wireless networks in the laptop stop displaying. The broadcasted SSIDs continue to show up though. All these users are using "Intel(R) Centrino(R) Advanced-N 6200 AGN" wireless cards with driver version I had upgraded one of the client drivers to the latest 15.1 version. However, he still complained about wireless disconnection (I am not sure about this problem as I didnt personally attend his laptop to know the cause of diconnect).

One another interesting incident is that 2 people from this test group were having a meeting in a conference room once and surprisingly both dropped at the same time with the same symptoms. The only fix was to reboot their PCs.

I have done following changes in my controllers hoping that the problem would get fixed, But still no luck.

1. Enabled client band select.

2. Checked EDRRM for A as well as B/G

3. Changed Channel allocation from freeze to auto.

4. Enabled "avoid persistent interferers".

In my calls with Cisco support we also ran debugs in the controller and sniffer captures in the client machine. All we see in the controller is that the client dropped without any reasons. Also, didnt find anything significant in the sniffer captures. At this point not sure what to do. If upgrading the client driver is an option, then I need to produce some proof or document to the management which says the current has known bugs to run 802.11n speeds. Scanned the entire internet, put a post in intel support site but no luck.

Any help would be highly appreciated.

Thanks a lot.

Cisco Employee

On intel client connecting wlan have only WPA2+AES, disable client band select and other options like exclusion, mfp,...

Try using different supplicant. try wzc/intel's/cisco's/Juniper's supplicant see which one giving stable performance.

you should be able to run/capture log on the PC for wireless disconnection.


I have a similar problem with at my clients' location.  The client PCs are Macs, ipads, iphones, smartphones and Intel PCs. 

The current cnclusion we can see:

-running a single channel between two APs (at least 15 cleints are connecting per AP); we have 133 APs running to two controllers.

-Client PCs are not disabling LAN when Wireless is enabled.

-Wireless hotspots on the Macs


I'll try out the WPA2+AES and WZC to see if they do the trick as well.

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