Google Nest Community

Correct. This doesn't have anything to do with old or new Google devices. Mine's, except the Google Home Max, are new gen devices.

Mine's just an standard Arris TG2492LG-LIB modem/router.

The same is happening to me on all Google devices (including a new Nest Hub 2nd Gen and a new Nest speaker). It began after I noticed an update to my Chromecast with Google TV. So far the only workaround I'd find is resetting/rebooting my router once...

They have proven time after time how mediocre they are.