SIRI on HomePod

About two weeks ago SIRI on my HomePod had stopped responding. At the same time, I stopped being able to log in to my Apple Extreme WiFi device. AppleTV is unaffected. My Mac is hardwired (ethernet) to my internet provider's device.

All OSs are up to date.

I have unplugged both devices in the hope that doing so would restart/reset them, to no avail. Can't find anything in Settings to help.