Hi. I've apparently got the same issue as mz3bo. As you can see on the following image:

My router is DIR-865L h/w: A1 f/w: 1.03 and on the DWA-182 i'm using f/w: 1.0
Below you can see my wireless settings:

And as you can see here, there is no mode reporting in the sofware accompanied with the DWA-182:

I used WPS when i installed the DWA-182, whitout any issues, and i rebooted both computer and router afterwards. My DIR-865L is well functioning.
And by the way if anybody know about some third party software that can detect ac modes, i would be glad to here about that too.