Prohibit wifi channel 5GHz in Japan is selectable

Technical Support for Routers
1

Hi

I purchased Flint through Amazon in Japan.
I can assign w52 channels statically but it seems w53 and w56 channels are not available for static channel.
In addition, there are some prohibit wifi channels(149, 153, 157, 161) are displayed in the drop down list.

How can I fix this?

2

The firmware version is 3.214 and I have already restarted it several times but not fixed.

3

Can you go to Luci and change radio country code to JP