I never had a chance to figure out why I couldn’t play tracks from Facebook or Spotify Play Button at home. After further research I found out that my DD-WRT flashed router had the “Deny DNS Rebinding” option enabled. Spotify needs to resolve *.spotilocal.com to 127.0.0.1.
In order to resolve it, I added this command to the DD-WRT startup options:
sed -i ‘s/stop-dns-rebind//g’ /tmp/dnsmasq.conf
Everything is good now, fortunately.