My desktop computer has a wired connection to the internet and so the built-in wifi card is normally not used. I decided to enable and use it as a wireless access point.
Unfortunately NetworkManager will only create an ad-hoc wifi network, and Android devices will only connect to infrastructure access points. Don’t ask why… A rooted Android phone or tablet can be configured to connect to an ad-hoc network, and if a separate program can configure a Linux box to act as an access point, NetworkManager should be able to do the same. As far as I can see, there are no good technical reasons for either of these deficiencies.
The solution is