HomePod timers “unavailable”

I got a few new HomePod Minis this holiday season and the timers have never successfully worked. At first the timers fur all devices just gave me a spinning wheel in the Home app, never loading, and now I have an error message (see attached screenshot):

Timers Unavailable

Timers can be viewed and managed only when this HomePod is on the same network as this phone.

Only they ARE on the same network, my home 5G network. And this error is appearing on ALL of my HomePod minis.

I’ve tried resetting the devices (seemed silly since this behavior has occurred since day one of use, but did it anyway), plus resetting both router and cable modem. Nothing fixes this.

These things have been drama since the day I set them up. I have to say, I’m pretty disappointed in this Apple product… but I’ve missed the return window and now I’m stuck with them.