Mopidy server is not being announced on the network

I have installed mopidy on my Ubuntu-server that is running at home. It works, I have connected to it with both mpd and http. But both Mopify and Remotefy can’t find the server on the network. I have opened the ports 6680, 6600 and 5353 (zeroconf) in ufw. I had another mopify-server running on another computer which where found by both apps. Accessing through a browser is not a problem. And I can connect to Mopify by manually adding ip-address and and port. The http-part is configured correctly (as far as I can see):

enabled = true
hostname = ::
port = 6680
static_dir =
zeroconf = Mopidy HTTP server on $hostname

Help would be appreciated.