How can I trouble shoot a debian hotspot?

Question

Creating a hotspot is much easier than I remember from the last time I did it, but I'm not sure how to trouble shoot this failure.

I was able to create an AP using nm-connection-editor. This worked great for connecting my Android phone, Arch laptop, and an older Mac. However, another android phone and a windows laptop are both unable to connect. The error is simply "Unable to connect." I've also been able to connect all the devices if I make the AP open, which is fine for testing but I don't want to run it like that indefinitely. I was also able to connect both phones prior to upgrading debian from 9 -> 10.

I don't see anything of interest in the debian logs. What are some good steps to narrow down the possible cause?

Answer 1

The error is simply "Unable to connect."

To get debug info on Android, I use MatLog (available in FDroid too)

On the Debian side, Hotspots can be handled with nmcli:

nmcli connection up Hotspot

You may get more info with

nmcli -t device show

See the manpage

I've been able to toggle the Hotspot On/Off in one click in Gnome, I can dig in my notes if you want, but the starting points were Argos and this script

Answer 2

I found this post on the pi exchange that is strikingly similar to my issue.

Though not absolute, it seems that wpa_supplicant doesn't support an authentication method for wpa2 but advertises wpa and wpa2 nonetheless. Old clients that only use wpa won't notice a difference, and some clients that will try both will succeed with wpa but others will try wpa2 have it fail and then give up.

I solved this issue by installing hostapd.