I don’t mean to sound ungrateful for your help, but there’s no way I’m going to go through the headache of a factory data reset. It’s just a terrible way to troubleshoot this kind of occasional problem.

Since the problem happens completely unpredictably, I could do this and not see the problem for a week and that means nothing about the possibility I would see it at one week one minute. Or I could see the problem in the first five minutes and that would get us only very marginally closer to identifying why the problem occurs since all it would do is eliminate unlikely candidate like some interaction between the WiFi calling stack and, say, the WeatherUnderground app.

OTOH, if I do this and spend the week waiting to see if this problem occurs, it will amount to a week living with an essentially stupid smartphone. (Worse than Safe Mode boot suggested earlier since even the Google stock apps and stuff will be clueless.) And, after that week, there’s the several hours necessary to put back all the settings that a restore after a factory data reset doesn’t restore. Been There, Done That.

Any other suggestions?