Until it didn’t, hours later. 
Here’s what finally resolved my problem:
Removing and reinstalling the micro USB power plug into the socket on the back of the cam.
I did it three times for good measure (“exercising” a plug/ socket combo costs nothing and can improve power connection quality if any flakiness from corrosion has occurred. Especially applies if you’re using a cam in “outlaw” mode (the cam is not Wyze approved/supported for outdoor use.)
I’m pretty confident this conclusion is correct because as soon as I physically grabbed the cam and held it in my hand a few feet from its mounting point, it was Happy Jack - strong and stable as the day is long.
Background: Cam is
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outdoors in a mild climate, second floor, under an eave - for four months with no connectivity problems.
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Has an SD card installed - approved size and duty rating. While I was there, I also “exercised” the SD card in its socket three times. Later, back in the easy chair, I reformatted the card via the in-app utility.
Coda: In the future, this is the first * second thing I will do if connectivity problems crop up. Even if it’s inconvenient to ladder-up, it’s far preferable to richarding around with arcane app and router settings for, um, hours, that often SEEM to fix something (because the problem is intermittent) but ultimately deposit you back into the same tech morale dump whence you started.)
Basic physical reality still matters! Everything else is built on-top of it.
* The first thing will be coming to these forums to see if known connectivity issues are being reported. Best to pour yourself a Jack’n’Coke and bask in some natural light for a couple of hours after initial discovery - after all, you could be the first one stung by a server outage, etc, ergo no reports will be on the forum yet. 
Extra credit:
Literally LOL’d. Clicking its link will lead you to the thread content that provoked it. 
[2 days later]
More intermittency…
When you do a factory reset, is the camera re-registered to (potentially) a different server (or pool) for authentication activities?
If not, what precisely does a factory reset reset?
Anyone?