I have a Sonos arc, Sub (Gen3) and two Era 100 speakers configured as a home theater with surround sound.  I bought a third Era 100 speaker only for the purpose of connecting a line-in from my Raspberry Pi so that I can play music from the Pi over to the Sonos home theater, since I cannot connect a line-in directly to one of the surround sound speakers.  However, it still won't work.  The line-in Era 100 speaker plays the music from the Pi but I get a "cannot connect. Try again later" type error message when I try to sync with the home theater.  Please help and thanks!