We use protected directories on nginx to offer client specific videos (mp4), using X-Accel-Redirect. On iOS 10 they don't play anymore - everything works fine on iOS 9.x and all desktop browsers, mac and pc. We already tried Firefox app and Chrome app, same behaviour, so it's not Safari specific but iOS 10. We debugged all passed variables, everything is correct. This issue only appears on protected videos. Other non-protected videos, that don't pass the X-Accel-Redirect are playing normally.
nginx 1.6.2, Debian 3.16.7, PHP 5.6.24, SSL
mabe related:
https://forums.developer.apple.com/thread/63652
https://forums.developer.apple.com/thread/60688