I have a B&O A9 speaker that I used to play with airplay. But when I try to use Spotify Connect to play music on it, it doesn't connect. I can see the speaker in the connect list on my Spotify iPad app. If I click on the speaker, it tries to connect for a couple of seconds and it jumps back to the iPad option.
The speaker is on the same wifi network and airplay works great. The firmware is up to date and the spotify app on the iPad is also up to date. My iPad is a mini with retina display with the latest ios.