Turns out my problem is covered in Troubleshooting.
Make sure you have multicast enabled. Some wireless routers require that you enable multicast (sometimes also labeled “IGMP”) in the web administration interface of the router. Others require firmware updates to enable multicast. Try updating your router to the latest version. As a testing point, if it works fine when the server and client are both on the wired side of the router, but it doesn’t work when one side is wired and the other side is wireless, then that points to the router as the culprit.
A quick firmware update on the router and we’re good.
Very cool app, thanks firefly