My question isn't about the fault, its about how to find it.

Yesterday I brought up a brand new Pi Zero 2 W and after a bit, it was all hunky dory.
Sometime last might, it went offline. No route to host.
I rebooted it and it lasted half an hour. Then it wouldn't reboot at all. Its now sitting next to the wifi router is configured for and is for now accessible.
I have no HDMI adapter for it., Its headless and normally accessible via ssh.
What I want to know is where in the logs to start looking for any issues?
The most interesting thing is that journalctl is full of unrelated messages *all the time I could not access* the PI Zero 2W
Mostly related to
Sep 13 11:12:24 PiFi2 systemd[715]: rpi-connect-wayvnc.service: Scheduled restart job, restart counter is at 1515.
Sep 13 11:12:24 PiFi2 systemd[715]: Stopped rpi-connect-wayvnc.service - WayVNC process used by Raspberry Pi Connect.
Sep 13 11:12:24 PiFi2 systemd[715]: Starting rpi-connect-wayvnc.service - WayVNC process used by Raspberry Pi Connect...
Sep 13 11:12:24 PiFi2 systemd[715]: rpi-connect-wayvnc.service: Control process exited, code=exited, status=1/FAILURE
Sep 13 11:12:24 PiFi2 systemd[715]: rpi-connect-wayvnc.service: Failed with result 'exit-code'.
Sep 13 11:12:24 PiFi2 systemd[715]: Failed to start rpi-connect-wayvnc.service - WayVNC process used by Raspberry Pi Connect.
That bunch was followed by an ssh session closed message. I didnt close the session.
[note: I have disabled VNC and wayland in raspi-config - how to remove vnc entirely?]
[Ah. apt-remove rpi-connect seems to work okay ]
So it appears that the machine was up, but simply wasn't connected TCP/IP/Wifi wise?
It did not respond even to pings. or presumably ARPS...
Ah. I found something.
Sep 13 09:42:54 PiFi2 NetworkManager[529]: <info>  [1726216974.2842] device (wlan0): Activation: (wifi) access point 'Larksrise' has security, but secrets are required.
Sep 13 09:42:54 PiFi2 NetworkManager[529]: <info>  [1726216974.2948] device (wlan0): Activation: (wifi) connection 'Larksrise' has security, and secrets exist.  No new secrets needed.
Sep 13 09:43:19 PiFi2 NetworkManager[529]: <warn>  [1726216999.7653] device (wlan0): Activation: (wifi) association took too long
Now googling suggest that may be randomized MAC addresses on the wlan0 interface, or 802.11n enabled on the router. Neither is active as far as I know.
*Well I have possibly fixed it.*
By explicitly creating
/etc/NetworkManager/conf.d/30-mac-randomization.conf as
[device-mac-randomization]
wifi.scan-rand-mac-address=no
So far it's stable after an hour or two
--
“The fundamental cause of the trouble in the modern world today is that the stupid are cocksure while the intelligent are full of doubt."
    - Bertrand Russell