Just in case anyone here is working or testing with multicast communications on Windows 8.1, I discovered a bug that somehow crept into the RTM build, Microsoft have confirmed it as have several other developers. Its a new bug, no previous version or build of Windows has ever contained it.
Attempting to use a DatagramSocket to get the output stream in order to then send a multicast message can fail with a “Host not found” exception from an “await” call.
Nobody knows why yet but Microsoft are looking at it.
I mention it here because its a shocking and serious fault in an area we all take for granted and if you fell victim to it while testing a system with a .Net MF project, its unlikely you’d suspect Windows until you’d spent days fiddling around .
I’m working on UPnP for Surface and Phone and it has prevented me from testing on a physical Surface device.