Thanks for posting here in the Google Nest Community.
I know how it feels when something isn’t working as it should. A few things: when did your issue begin? Which Nest speaker/display do you own? Are you getting the same message when using your phone’s Google assistant? Are other third party devices working?
You can do a sequential reboot. First, unplug your Nest speakers/ displays for 30 seconds, then do the same thing to your Wi-Fi router to refresh both devices and your Wi-Fi signal.
Looking forward to your response.