Is there ANY way to tell who is downloading and syncing from you?

[beckfield]

I think the Tautulli app might have what you need.

Tautulli - Monitor your Plex Media Server

Tautulli A python based web application for monitoring, analytics and notifications for Plex Media Server. Features Responsive web design viewable on desktop, tablet and mobile web browsers. Themed to complement Plex/Web. Easy configuration setup (no separate web server required). Monitor current Plex Media Server activity. Fully customizable notifications for stream activity and recently added media. Top statistics on home page with configurable duration and measurement metric. Global watchin…