Remote play on different Apps not working or laggy

[ElNino]

Hi everyone

I have Jellyfin running in a docker container. Remote access made through Nginx Proxy Manager. My friends can access the server and play media in the browser. I myself access it locally with browser or a nvidia Shield, everything working fine. I can also access it with my iPhone through WiFi with the Jellyfin App, no issues.

But when I try to access it via Cellular, I see all the media but when I want to play something it does not start. In the Jellyfin Dashboard I see the connection, it also starts transcoding, but nothing appears on the phone. One of my friends has an Android Phone, exactly the same issue (but he is connected to his WiFi, so no cellular). Also another friends has the same issue while using some kind of Android TV box. It seems like remote access works best with just a browser. Apps of some kind seem to be ether not starting at all or have a short lag every few seconds.

How best track this down?

This is my NPM config:
SSL with HTTP/2 Support
client_max_body_size 0;
proxy_buffering off;
proxy_request_buffering off;
# Security headers recommended for Jellyfin
add_header X-Frame-Options "SAMEORIGIN";
add_header X-Content-Type-Options "nosniff";
add_header X-XSS-Protection "1; mode=block";

System on my side is quite powerful, internet is 1Gb symmetrical.

Any help much appreciated.

[TheDreadPirate]

Can you share your jellyfin server logs and ffmpeg logs via pastebin? And share screenshots of your Nginx Proxy Manager config, but censor the domain. One common misconfiguration is enabled "cache assets" in Nginx. This is not recommended for services that stream media.