Recently installed a new modem/router. Updated Sonos app to the most recent version. Did a factory reset on my Gen 5’s and Roam. Everything goes well for the addition of the Sonos components to my new wifi network until the very end when it indicates that neither the Gen 5’s or Roam could not be registered to my account. I have a Sonos Port hardwired with an  Ethernet cable into the modem/router. 
Other device connections were successful. These included 2 Apple TV’s, iPads, iPhones, audio visual receiver and wireless printer. The only failures were the Sonos speakers.