I have two Audios paired in my home office. About a week ago they randomly started playing the startup sound. It happens every hour or so, day and night, and it happens while the device is in use. I'll be listening to music, and it'll play the sound over the top of my music.
I've rebooted both devices, unpaired and re-paired them, and even disabled notification sounds in the app.
I'm at a loss of what else to try.
That certainly isn't the experience we want you to have and we're here to help whatever way we can.
A few questions: does the trigger occur during a particular time of day, randomly or as you've mentioned, just when playing music? What kind of environment does the device fail in? is it noisy or quiet or just mild? Are you the only one who has control over your devices? I know that you've somewhat done this already but, it would help a lot if you could do a sequential reboot. Unplug the power cord of your router followed by your Nest speakers. Plug them back in after 10 minutes tops. Restarting your phone might also help. Monitor afterwards.
If the issue persists, check its log by following the steps below and get a screenshot:
Keep us posted.