The most basic reasons could be:
- a limited internet upload bandwidth for your Plex Media Server
- client quality settings limiting remote/internet streaming quality
Some additional troubleshooting:
-
can you verify if the remote stream is possibly relayed? this can happen if the client cannot see/access your server directly – in that case Plex will display the stream as
indirecton the server’s “Now Playing” dashboard.
https://support.plex.tv/articles/200871837-status-and-dashboard/ -
review your remote access setup → The Basics of Remote Access Troubleshooting
