Before Sonos firmware 45.1-56150, there were some interoperability issues with Sonos when we switch the channels in the Plume network as part of the optimization process. Sonos devices were not able to accept these Channel Switch Announcements (CSAs) that well, which resulted in Sonos disconnections from the network.
If you are connecting Sonos to your Plume network using WiFi, make sure all your Sonos devices are running firmware 45.1-56150 or later.