Intermittent and I haven’t nailed down all the symptoms. Once before, and several times this evening, my relatively new Nova has misbehaved. It generally begins with the music stopping and restarting in a manner similar to a rebuffering issue. But then it stops playing entirely. The white light in the dial control on the top starts spinning. The Nova disappears from the app. On one occasion I did a deep sleep, but it didn’t help - at least not immediately. On another occasion the buttons on the front of the unit became unresponsive, including the sleep button. At some point each time, it has returned to normal.
The Nova is connected via Ethernet to the satellite of a NetGear Orbi. I am playing music from a DLNA server on the same network.