I don't know anything about your system stuartg... but maybe my system can offer some clues of where to look for your problems...
My Annex 'Sentry' alarm has an RTC module and TM display giving a live clock 24/7, which has been running standalone ok for more than a year, announcing visitors over a distributed TTS audio system.
A Watchdog monitors the Sentry 24/7 and can reboot it if needed, and log any failures.
A RouterDog similarly monitors and can remotely reboot the routers if needed.
They (and others) sync time to the second with the Sentry RTC at startup, plus any time any other device starts up or re-syncs (I prefer my system isolated from the internet).
The Sentry Log records all device startups, and all sensor events, to file for viewing by remote browser. So there's a lot of activity and interaction going on, all without problems.
Sometimes I use a Win10 laptop to view and clear the Sentry Log, and once or twice have used an Android phone, but usually it will either be directly from my MX Linux Firefox browser, or else from Firefox in a Win7 virtual machine running in VMware on MX Linux.
The important point I'm making is that I very much depend on my system, which is computer independent, very reliable, and its mix of Annex devices keep going wonderfully.
BUT NOT IF I KEEP BROWSER CONNECTIONS OPEN.
I have found that keeping websocket connections open between device and browser is like continuously twisting up a tourniquet... something will eventually break.
It may keep struggling along for days, but inevitably
Any device with an Output web page websocket connection which is continuously updating (such as the second hands of a clock) is best closed when no longer needed.
If multiple webpages are opened to multiple devices, they can all be disconnected by closing down the browsers multiple tabs, then when the browser is reloaded with all its previous tabs, only those which are freshly revisited will actually reconnect their websockets again (so don't close the browser with an Annex tab active, else it will be reconnected when the browser starts up again).
Another option is to specifically close all pages when done and relaunch them from shortcut icons created on your desktop.
There is currently no way to disable html logging other than manually checking Stop Log checkbox
in the Editor page, so BE AWARE that every time you close an Editor page, the Stop Log checkbox defaults to unchecked again, and will be echoing all your browser writes (every second if you are displaying clock seconds) to the log window until you remember to manually Stop Log again.
(preferably by cycling power), and don't forget to Stop Log again after reconnecting.