So many problems with my router...
A firmware update several months ago resulted in an inability to establish 5G WiFi if the 2.4G SSID was disabled. [ongoing]
Also the option to have automatic channel selection on 5G has vanished. [ongoing]

In the last week, I've found all my WiFi devices have been disconnected many times. Switching off and on again WiFi sometimes works. Otherwise reboot the router.
During the outage, the admin/status page shows 5G Wifi is enabled, but all diagnostics show no SSID.

These 5G WiFi aborts are now happening at least once every 24 hours.
The router is borderline not-fit-for-purpose.

What to do?

P.S. Also discovered that the press-button to toggle on/off the 2.4G/5G wifi...does nothing. Press and long hold sems to activate WPS... but the button does nothing else