The music player works correctly for local files (MP3 format suffers from the looping bug reported elsewhere, OGG works okay but the player is very quiet)

But the moment I put in a remote URL (both HTTP and HTTPS tested, on Steam Cloud and other web hosts) I get the error "WWW AudioClip Error: Cannot connect to destination host"
None of my Windows-using friends get this error, and this error stops the music from playing for all players even if I'm Spectator. (The Music Player should probably not be stopped by spectators regardless.)
I have no firewalls and the URLs download correctly through web browser just fine.