Ring Spotlight Cam no live view etc

To Ring Customer Service and community: A Spotlight cam I installed last week (hard-wired, 100mbps speed) worked as it should for a week but in last two days is up and down, mostly down (but not showing offl;ine); when down has power no live view, no camera previews generated, no siren or alerts, then comes back (twice overnight) works normally but now today has been dysfunctional for five hours with same issues as above, albeit with net and power working fine and settings showing connected. The other four of the same cam I installed at same time with same conditions and cam settings work as they should. Have restarted errant one repeatedly (so has power and net) but to no avail. Is it a dud cam? I can't do any more than what I have done repeatedly...