@Carl - thanks for replying. I finally got some time today and discovered an Apple doc about how to set up a router for their stuff. I discovered that Apple devices REALLY don't like the Access Control feature now (they have a long, questionable explanation based on today's hackers as to why they're right and router mfg's should never have bothered to put it in anyway). I had it working fine for several months, but I touched something (not sure what the trigger was) and it totally broke for everything Apple. After I turned off Access Control, they worked fine. Maybe if I wasted a lot more time, I could recreate the usable Access Control setup, but for now, I turned it off (maybe it's a new security "feature" of iOS 16.3.1?).

The Apple doc wasn't perfect, however, because they claimed that they wanted the same SSID for all the channels and that ISN'T true. If you do that, Apple only logs into the 2.4GHz band and you never get the 5 GHz band, even with different passwords (logging in with same SSID but different password for the band you want). For Apple devices to use both bands, you need unique names for the two bands and then login to the band you want to use.

I got into all of this because my modem gagged and after zero help from Cox Cable, I did a hard reset on the modem (pressed the modem reset button with a paper clip, not just pull the power cable and restore it) and was able to get back online, at least with my desktop.

Thanks again for your help...

  @Carl my Apples do work on a unified network, but only in the 2.4 GHz band for me. There is probably a magical setting somewhere that could get mine to work on both bands, defaulting to the highest speed, but I'm not willing to spend anymore time on them when the problem is already solved - two names vs one. Looking at the local WiFi nets, I'm sure I'm last on the hacker's list of easy targets (they have no passwords, default net names, etc).