I have two Amazon Echo Dots let's call them #1 and #2. Ever since I added #2, Spotify seems to lose #1 as a valid device periodically. On my phone, only Echo Dot #2 will show up as a device. And having Echo Dot #1 play Spotify is just silence.
I have a lot of devices in my house. I'd really prefer a way to tell Spotify which devices are valid. Becaues it picks up all my TV Chromecasts, but I'll never cast music there. It seems like Spotify has a 6 or 7 device limit.