Connecting from Pi OS to a wireless hotspot on Ubuntu MATE 20.04

I am currently unable to connect from my Pi 4 w/- Pi OS (buster) to a hotspot on a Ubuntu MATE 20.04 machine (laptop).

The Ubuntu MATE hotspot was set up with a WPA/WPA2 passphrase; using the desktop connection manager.

I have been able to connect to the Ubuntu MATE 20.04 hotspot from my Android device.

The hotspot is visible to the Pi OS. However, when I enter the passphrase, I merely get a popup error saying the network could not be reconfigured.

I am also able to connect to other hotspots with my Pi 4.

Any help with debugging this or solving this would be greatly appreciated.

To clarify, here's what does and doesn't work afaik:

        | Android hotspot | Laptop (MATE 20.04) hotspot |
--------|-----------------|-----------------------------|
Pi      |        Y        |               N             |
Laptop  |        Y        |               -             |
Android |        -        |               Y             |

Not much progress. To elaborate on where the problem occurs:

  1. I configure a wireless hotspot via NetworkManager GUI on Ubuntu MATE 20.04 (laptop)
  2. I turn on wi-fi on the Pi, and the hotspot is visible.
  3. I attempt to connect to the hotspot, but after I enter the passphrase, nothing happens.

I've checked what's going on while I do this on both the Pi and laptop as best I can.

  • journalctl: the only clue is that the laptop gives me:

    wlp3s0: AP-STA-POSSIBLE-PSK-MISMATCH ...

  • iwlist wlan0 scanning (on the Pi) which had this:

    IE: IEEE 802.11i/WPA2 Version 1
        Group Cipher: TKIP
        Pairwise Ciphers (2) : CCMP TKIP
        Authentication Suites (2) : PSK unknown (6)
    IE: WPA Version 1
        Group Cipher : TKIP
        Pairwise Ciphers (2) : CCMP TKIP
        Authentication Suites (1) : PSK
    

It seems like there's some sort of problem with the authentication perhaps? What does "PSK unknown (6)" mean?

Another update:

I created a network on the laptop with no authentication requirement, and the Pi was able to connect. Obviously this is not a solution - but it provides evidence that the problem is with WPA/WPA2.