WLAN showing up as 802.11a/g but not 11n

[codflanglers]

Using a wifi scanner like Metageek inssider or chanalyser, I'm seeing one of our WLANs as only 802.11a or g but not 802.11n like it should be.

All the other SSIDs on that AP/controller are showing as 802.11n. I can't for the life of me think how this could be, but the scanner is showing the top data rate as 54Mbps. Connect to another SSID and it shows the upper data rates as well. 

Any ideas why this would be? Typically this just happens to be our main SSID. Is it just the scanner interpreting things wrong? I've looked at the controller and the upper data rates are enabled for 802.11n as well as 40MHz for the 5GHz radio.

[Stephen Rodriguez]

And that WLAN has WPA2/AES and WMM is allowed?

Steve

[codflanglers]

It's WPA2/AES but WMM is not allowed (Cisco TAC had me remove that option to resolve a bug).

[Stephen Rodriguez · Accepted solution]

WMM has to be at least allowed for 802.11n rates to work.

Steve