Unable to connect to wifi

Hello
I have an airgradient one, I-9PSL. After a bit of trial and error I managed to update the firmware from 3.1.1 to 3.1.9. But a persistent problem, from when I first powered it on, using v.3.1.1 is that the monitor will not connect to my wifi.
I am utterly flummoxed by this. And I hope the wiseheads here may be able to assist with a solution. I am sure it is going to be simple.

My system is:
Ubuntu, 24.04 - fully up to date, on a laptop.
Internet is provided by a pixel 4G connected to the lap top via USB tethering [I live where there is no reliable broadband, but paradoxically, quite good 4G]
I am attempting to the laptop wifi to connect to the airgradient.
Sequence & behaviour
I power on the airgradient. It goes through its initialisation sequence and finally gets to:
“Connecting to WiFi”
I open my Network Manager.
At this juncture, my laptop “sees” the airgradient.
There is a single blue LED on the airgradient.
I click on it in the Network Manager list of
“Visible Networks” on my laptop.
The single blue LED becomes a line of blue LEDs.
The laptop shows that the airgradient is connected. I can check the connection and see all sort of information about the connection, the speed, the encryption and so on.
BUT:
On the airgradient display, the 180 sec countdown is running and saying:
[second count] to connect to WiFi hotspot:
airgradient-[monitor specific number]
The airgradient seems to be hunting for a WiFi connection.
The counter runs down to zero.
The LEDs turn into a red line.
The airgradient reboots. And it all starts again.
I have tried this while the airgradient is connected to the laptop via the supplied USB cable and also when the airgradient is powered by an external source (and not physically connected to the laptop.)
In my browser, I can connect to the airgradient via http://192.168.4.1, while the laptop shows the airgradient is connected to the laptop (even though the airgradient thinks it is not connected).
The log from the console tells this story:
Detected ONE_INDOOR
[OledDisplay] Info: begin
Firmware Version: 3.1.9
LED bar brightness: 100
Init SGP41 success
initializing PM sensor
cleared 0 byte(s)
setting active mode
7 byte(s) written
Set S8 AbcDays successful
[ApiClient] Info: Init apiRoot: http://hw.airgradient.com
[ApiClient] Info: begin
*wm:AutoConnect
*wm:Connecting to SAVED AP: airgradient
E (14605) wifi:sta is connecting, return error
[ 11446][E][WiFiSTA.cpp:317] begin(): connect failed! 0x3007
*wm:AutoConnect: FAILED for 15602 ms
*wm:StartAP with SSID: airgradient-[DeviceID]
*wm:AP IP address: 192.168.4.1
*wm:Starting Web Portal
[WifiConnector] Info: Wait for configure portal

When I do a iwlist scan (via terminal)of my WiFi adapter on my laptop, the following is thrown up:
Cell 01 - Address: 84:FC:E6:0D:50:BD
Channel:1
Frequency:2.412 GHz (Channel 1)
Quality=70/70 Signal level=-27 dBm
Encryption key:on
ESSID:“airgradient-[DeviceID]”
Bit Rates:5.5 Mb/s; 11 Mb/s; 1 Mb/s; 2 Mb/s; 6 Mb/s
12 Mb/s; 24 Mb/s; 48 Mb/s
Bit Rates:54 Mb/s; 9 Mb/s; 18 Mb/s; 36 Mb/s
Mode:Master

IE: IEEE 802.11i/WPA2 Version 1
Group Cipher : CCMP
Pairwise Ciphers (1) : CCMP
Authentication Suites (1) : PSK

Hi there. I’ve just spent over a day trying to work out why the airgradient won’t connect. I am unhappy to report that I have not idea why it wont connect.
I have tried two different USB wifi adaptors as well as an access point, in addition to the wifi adapter in my laptop. In each case the adapter can “see” the airgradient, but when I enter the password (cleanair) the connection is not authenticated. There is no error message the pasword is wrong. The airgradient does not accept it or recognise that a password has been sent back to it.
I have re-flashed the airgradient and the off line mode is relatively stable but the readings vary from an aranet monitor I have.
For temperature, the Aranet reads about 1 deg C lower
For CO2, the Aranet read about 35 ppm higher
For RH, the Aranet is about 3% or 4% lower.
Anyways, I’ll check on the forum from time to time, particularly when a new update appears, but for now, the airgradient will go and live with the other pieces of not working technology in a cupboard.

In my case, the airgradient seems to be causing downtime for my wifi. I have modern asus routers running in a mesh. Since plugging the device for the first time I have had tens of periods with my wifi 2,4 ghz being down for some time. Few days ago, I unplugged it, restarted my routers and since then wifi has been stable.

I would appreciate someone looking into it and fixing the firmware or something.