"channel [21] (157) is disabled for use in AP mode"

[Arend van Spriel]

On 04/28/2013 06:06 PM, Zack Buhman wrote:
> On Sun, Apr 28, 2013 at 03:58:43PM +0300, Jouni Malinen wrote:
>> The passive scanning part there indicates that no radiation can be
>> initiated on the channel (i.e., need to see a master device operating on
>> the channel before transmitting any frames).
>
> I find this information extremely useful; thank you.
>
>> It's not hostapd, but the regulatory code or driver that has marked the
>> channel as not allowed for AP mode:
>> 5785 MHz [157] (17.0 dBm) (passive scanning, no IBSS)
>
> But the regulatory code did no such thing (so far as I can tell); that
> iw list output doesn't at all match the iw reg get. Wireless-regdb [2]
> doesn't define passive-scanning anywhere in the US regdom, and according
> to iw list [1], there's in fact exactly zero 5GHz channels that I can
> use in AP mode (all either disabled or passive scanning). Why?

Also the driver can set a custom regulatory domain so that may be the 
case for your device.

Regards,
Arend