If you select Auto in the “Channel” Option, the router does not automatically select the DFS channel.
The “Allow DFS Channel” switch is a Fool-proofing design.
Selecting the DFS channel will cause the WiFi to be temporarily turned off. So to avoid misuse, users need to turn it on manually every time they switch from non-DFS channel to DFS channel.
If you feel that this is misleading, we will review the interaction design here.