Hostapd Application AP setup not working for channels 100 and above

Jouni Malinen j at
Wed Aug 25 02:41:07 PDT 2021

On Tue, Aug 10, 2021 at 12:36:26AM +0000, Nagaraj Subas Chandrabose wrote:
> I tried to set up a Linux based Variscite DART-6UL board WIFI as an access point using the hostapd.conf file and the hostapd(Ver: 2.9-rc0) application. In the hostapd.conf file, I made the following modifications:

> However, the hostapd application seems to be not working if I attempt to set the channel to 100 and higher. 
> channel=100
> The messages logged by the hostapd application are
> Mode: IEEE 802.11a  Channel: 100  Frequency: 5500 MHz
> hostapd_handle_dfs_offload: iface->cac_started: 0
> hostapd_handle_dfs_offload: freq 5500 MHz requires DFS
> hostapd_setup_interface_complete_sync: Wait for CAC to complete

> Because the DFS-CAC is not yet up and running, the HOSTAPD application is unable to complete the AP/channel setup configuration. The system is unable to start/complete the DFS-CAC functionality despite having the DFS-CAC option enabled in the conf file. As a result, the hostapd programme is always waiting for the system to complete DFS-CAC configuration. Is there a problem with the hospad programme, or do I need to enable any other settings?

Does the Wi-Fi hardware and driver used on that system support operation
on DFS channels and in particular, radar detection?

Jouni Malinen                                            PGP id EFC895FA

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