I was excited that Spotify said it now performs multiroom playback on Amazon Echo devices, but when I purchased a second Echo and actually tried it, I got very bad results. 

The Amazon "Everywhere" group does work without problem with TuneIn and other applications.  And at first, Spotify recognizes the Everywhere group, lists it as a device in Spotify Connect, and plays on both speakers.  But then it just quits, in the middle of a song, or after a pause of some time.  100% of the time, Spotify Connect fails to connect to the Everywhere group in the morning after not playing overnight.  You see each Echo on the device list but not the Everywhere group, and Spotify won't play on both speakers even when Alexa is sending to the Everywhere group. 

To get it back, what you have to do is go around the house and reboot all the Echo devices at once -- unplugging them and then replugging them.  Then it works for a while but quits again by the next day. 

So it's not my network or devices, and it's not Amazon or the Echo.  Spotify is not working the way Spotify says it should.  I hope someone at Spotify recognizes responsibility for this and fixes the addressing systems conflict or whatever it is.  Any help would be appreciated.  Thank you.