My problem was indeed no Wi-Fi on the offending device. However, that device is perpetually on and connected and decided for unknown reason to disconnect. This is not behavior I expect to go unannounced on an Apple device. I have 7 of them in constant use. Babysitting each and every one to see if they have done something odd and stupid is just not part of my life plan.
I save a document, check to see it is saved, and I leave the office with my iPad, iPhone and head out to work, absolutely certain that once I get there I will be able to refer to my document. Troubleshooting every single conceivable purpose for a failure, every single day of my life is not in line with my choice of purchasing Apple’s expensive devices. Seeing a notice that a member of my own network is offline seems obvious. Visiting a checklist for every misbehavior is not at all obvious.