Well, I eventually got a replacement camera from Google.
Set it up, and experiencing exactly the same issue.
Once or twice a day, it will disconnect and reconnect - same log entries as shown before.
The problem is that I get a push alert every time - and I can't turn it off as I would then not be alerted to a real problem with the camera. Very frustrating.
From what I can see, the signal is strong - it is only about 35 feet away from the MR18
I would appreciate any ideas - as it appears it is something with the Meraki...