How to connect Android App from WAN

Hi ,can you help me i can not connect from WAN to my server before in Emby i was able to see my external login link and when i type it to the app just work.
I am using Unraid server with Jyllyfin docker and Letsencrypt docker and i setup reverse proxy with DuckDns and i can connect from outside perfect and to watch IPTV even everything is working.The problem is only android app i try all combinations with IP and domains and with ports and without i forward ports to my Pfsense and nothing works.
Thank you.

Are you able to access it through the web browser externally?

What program are you using for the reverse proxy?

Hi,anthonylavado

Thank you for you answer .
I use Letsencrypt reverse proxy and using it also for Bitwarden docker and Nextcloud docker and last i setup for Jellyfin and everything was accesable from WAN from any browser Mozilla ,Chrome, etc…
Then i try android app and cant connect.
Today maybe update broke also access from browsers only on Jellyfin the other dockers works perfect.

When i try to access from WAN i get

Value cannot be null.
Parameter name : netmask
I can access Jellyfin from Lan with IP and Duckdns domain but the WAN only broke.

I dont know what to do now how to fix it.
Where i can find the GO file in the config folder?
Some movies i get them a bit pixelized i dont know why.Mibox 4 and Samsung TV on Lan.
Thank you very much for your help.

Edit: Fixed by reinstalling the container and delete the Appdata folder and install again .
Now the app connect from first time.
I think sometimes is good to reinstall and start from zero time to time then we can avoid some problems during updates.