Rekordbox Not Working With Duxbury Router

Unfortunately, Pioneer can not guarantee the performance of the rekordbox link when used with 3rd-party networking hardware, as some devices offer network security or traffic shaping that may interfere with rekordbox data. As you note, the RX works when connected directly, but not via the router, so it's clearly the router causing a problem. Please consider using another network switch or router which may allow the devices to communicate.