Why am I insisting on 17.9.3 or newer release? There was an issue, which prevented Site Survey mode from working on ROW regulatory domain APs used in the UK. The AP simply won’t accept the GB country code, and it won’t enable 5 GHz and 6 GHz radios. This is fixed in 17.9.3.
That error message it literally telling you what to do! First change the Channel Selection from auto to whatever the options are there - manual or channel number? After that it should allow you to change the channel width.
Having said that - what exactly had you changed when you got that error message? (I assumed you had tried to change the channel width)
And just in case - presume you have tried different browsers and versions and not blocking cookies because that can account for some strange GUI problems. Also try clearing cookies and cache and then re-starting the browser to be sure.
Why am I insisting on 17.9.3 or newer release? There was an issue, which prevented Site Survey mode from working on ROW regulatory domain APs used in the UK. The AP simply won’t accept the GB country code, and it won’t enable 5 GHz and 6 GHz radios. This is fixed in 17.9.3.
Good spot @MM15 and agreed that 17.9.3 is the right version to use anyway, but actually Jiri's blog mentions the real reason for the problem you encountered - your country code was not set. The bug Jiri refers to is https://bst.cloudapps.cisco.com/bugsearch/bug/CSCwd24606 which is specific to the UK after UK left EU (17.9.2 thought GB was still part of -E domain). Foreign language on the error message you see makes me think you're unlikely to be in the UK.
The AP will not allow 5 or 6 GHz to be used until the country is selected so that it knows which regulatory domain settings to use. We can see from your original screen shot that you had not selected the country code and that's why you couldn't set 5/6GHz. Use cli "configure ap country-code XX" to configure your country on ROW AP.
