Spotify Connect is not working

[PaddiTheInsane]

Hello,

I'm using Spotify Connect with a Denon X4100W AV-Receiver and in another room with Google Chromecast and with a Yamaha WX-030WH (a network speaker) in the kitchen.

When I select one of those devices via smartphone or the Windows appliaction, it stops sporadically (sometimes it's working for hours or it stops already after a couple of songs).

 So this must be definitely a Spotify Connect problem!

I'm using a Fritzbox 6490 Cable as my router and the problem appears with every tried device.

Please help me.