[22.04] NetworkManager hotspot no longer allows connections from Android, Linux clients

[jacobgkau]

After upgrading to 22.04, my Android phone and other Linux machines will no longer connect to a hotspot sharing an Ethernet connection over WiFi. The Android phone says "Can't connect to network" after a few seconds, and Linux machines prompt for the authentication passphrase over and over as if I'm inputting the passphrase incorrectly.

I started having this issue on my Arch Linux desktop a few months ago, so it seems whatever component caused the issue has now made its way further downstream into Pop!_OS. I suspect it's something like NetworkManager; the desktop is running KDE and using dnsmasq instead of systemd-resolved, so I don't think it's systemd-resolved or GNOME Control Center in particular. On the desktop, I had partial success switching from NetworkManager to hostapd to create the hotspot (suggesting it's not necessarily a driver issue), but the routing/NAT configuration for that was more complicated than using NetworkManager's own hostpot functionality.