I solved it! Switched to Tracfone for $15/mo unlimited talk and text and
1 GB data (other options available) and got a refurbished Samsung Galaxy
phone for $14.95.
UPDATE MAY 2022: SEE post below. Switched to Tracfone and been using a
month. No issues. At all. Ditto. I had this problem about a year ago,
then it was fine for several months, now doing it again regularly.
Sometimes multiple times during the course...