Draytek 2750 and Sonos / LastFM

Hi,

I have a new Draytek 2750 VDSL2 modem / router.

Sonos system is up and running fine (all components found). Only problem is, Spotify and Last FM and regular radio are not working ("unable to browse music" messages and similar).

Any ideas? Is my router blocking access to Spotify / Last FM somehow?

Thanks!