It's a hardware issue. None of those steps has helped or will help. I recommend reading these sources to see the extent of the issue, how many different people have tried different solutions, and that none of those steps has worked.
The best theory I've heard is that Nest Audio speakers' internal circuitry can't handle normal fluctuations in AC power, resulting in a sputtering DAC. It's hard to test this theory without equipment that ordinary users wouldn't have, but it's the only remaining plausible way to explain why Nest Audio can't do something -- namely, play music -- that MP3 players have done well for nearly 30 years.
I'll also add that my household has Nest Audio speakers connected to Google Wifi APs, driven by Pixel phones. Upstream is an AT&T fiber connection whose only issue in years was a physically disconnected wire outside my property. This is 100% a Google problem, possibly a Google ecosystem problem.
Dan: I know you don't work for Google, but don't you think that for the good of the world, it would be better to ask one Google engineer to try to reproduce this common problem, than to keep asking individual Google users to unplug, reboot, and reset their speakers? Why not go to the source of the problem so that it can be fixed for everyone (perhaps by offering replacement for faulty hardware if software updates can't fix it)?
