When trying to stream music from https://play.spotify.com through a ProxySG appliance, the Spotify web page presents an error that it is having an issue streaming music.
Error message: Sorry, but it seems that we cannot stream music to you at this time. This is probably because of restrictions placed on your network, but we are working on ways to get around this.
Spotify music streaming traffic is sent directly to Spotify on TCP port 1935 (RTMP) and ignores the browser's explicit proxy settings.
To allow this traffic to traverse your network, you can (if your enterprise security policies permit) enable users to connect directly to spotify's servers on port 1935 directly.
Allow direct RTMP 1935 traffic through Internet Firewall or Router.