Play-fi speakers not shown on Spotify's Device List

[poulsbo2]

My DTS Play-fi speakers cannot be seen in Spotify's device list.  These speakers are on the same wi-fi network as my Amazon Echo Dot speakers which I can see on the devices list. What do I need to do to get these to show up on the list?

[Cooper_da]

If have kind of the same problem. 

My Sonos speaker is shown in the spotify android app, my echo dots are not shown. 

All speakers play spotify music on voice command. 

On my iphone (not longer accessible) all speakers including the echo dots were shown. 

Any idea why the speakers are not shown on android app?