Really need to read the Optimization & Performance Guide on this one. I think itās more that the Relay can support 5000 endpoints given the cores/RAM, AND youāve applied the OS tuning for the relay (shortening the TCP TIME_WAIT delay, increasing the range of Ephemeral ports, etc.)
FWIW, Iāve already relays running up to 2000 clients per each, having applied most of the OS tuning several years ago. Itās not a recommended configuration, but itās always been āpossibleā though your mileage may vary of course.
I think thereās also stuff in the guide about tuning reporting frequency on the clients, batch counts on the relays, etc.