SOLVED: MKV files wont play in Android client app when accessed through NGINX reverse proxy

[TheDreadPirate]

Remove these security options.

Code:

add_header X-XSS-Protection "1; mode=block" always;
add_header X-Frame-Options SAMEORIGIN always;

These are both known to be problematic with some clients.

This one MIGHT also be an issue.

Code:

add_header Referrer-Policy "no-referrer" always;

https://jellyfin.org/docs/general/networ...exampleorg

Also make sure your phone is set to use the integrated player and not the web player.  Settings > Client settings.