Update:
Well, it happened again. "No WWAN. But I didn’t update/upgrade.
Cutting it short, I opened Settings > Mobile where it says “No WWAN adapter found”. I noticed there is a button at top left {CORRECTION: Should read ‘at top right’. It was in Off position.
I tapped it and voila!
No idea why it would have shut off. All I do with this is let it sit on the cradle and once a week I take it out with me at brunch so I’m not the only one at the twiddling her thumbs while others are texting each other.
Of note is that someone said they sent me 3 pics. I checked and nothing new had come in. They tried one more time. Nothing. That’s when I noticed a white line through the 6 mobile bars.
Checked Mobile and found the “No WWAN adapter found” I didn’t notice the On/Off button icon. Did all the normal tweaks and and finally saw the button as as stated, tapped it and it was back on.
When I checked for the pics, there are over 50 of them. I stopped counting at 50. First, 3 pics in one text message came in right after I tapped the On icon. The rest must have come in later, possibly the the ISP send and when not received, tries again a few times.
I guess it’s a trade off. Maybe something must be out of wack somewhere at all times. 
~s
A late thought. When I went to Settings > Mobile and saw the “No WWAN adapter found”, it was easy to miss the On/Off greyed out icon (top right). I would like to see the text in the No WWAN message have “Is the Mobile toggled on” - sort of like when we try to take a pic if camera switch is Off we get a similar message.