How do I enable the Access Control on the router?

I would also like to see a screen capture, because.......

although I have never enabled Access Control on my Orbi, I discovered one day that a device was "not working".  Upon further investigation, it appeared that Access Control had been enabled!  But, how?  What appeared to have happened was that my clumsy fingers had somehow "swiped" the little green bar next to that device and "blocked" it, which in also turned on Access Control.  Very frustrating!

So, what HappyCat​ might be looking for is evidence that the user has accidentally blocked that device without meaning to.