Playing around with Html5 audio element on Chromecast with the source pointing to my instance of a Subsonic music server. You can set the music server to serve over http or https. If https, the audio element won't play. I've read a whole bunch on certificates etc but still not getting to a solution. The MediaPlayer in an Android app handles this fine (without any certificate) but on Chromecast with the Html5 audio element it doesn't work. Need some direction...
Not gonna like this answer, but Chromecast simply won't support self-signed certs. It is built into the Chromium security model. IF you can get a cert side-loaded into the cert store, it would work (Android and Fire Tablet and TV can do this), it might help, but Chromecast (and FireStick) can't do that.