UPnP AV is one of the oldest streaming audio standards still in use and it is showing its age. Complicating the issue is the fact that the UPnP standard is pretty loose. The effort required to support one device may be substantially different from the effort required to support the next if they implement different optional subsets of the standard.
Most UPnP devices really want to have direct access to seekable, random-access media files. Many of the features we support, such as streaming content, DSP, gapless playback, and DRM, are in conflict with this rigid expectation. UPnP is unique in working this way–the more modern standards like AirPlay, Linn Songcast, Google Cast, Meridian Streaming, RoonSpeakers, and AIR allow for significantly less variation on the part of the hardware manufacturer, and support more flexible audio streaming models that allow us to integrate them with few or no compromises in user experience.
Nevertheless, we’re aware of how important UPnP support is to the owners of those devices and we would like to support as many UPnP AV devices as possible. Developing workarounds that may allow us to play nicely with many of them is a priority, but it is not expected that we will include support for UPnP AV devices at launch.
This thread sets out the issues associated with supporting UPnP and DLNA.
Brian’s conclusion was:
So on the whole, even if we expended the technical effort, I have my doubts that we could ever get to a place where we confidently say “We support UPnP” and our users can confidently buy UPnP stuff and know that it will work. And lots and lots of time will go down to toilet getting from where we are to that (disappointing) final outcome.
I never say never…but I don’t want to push out bad product, or product we can’t support well. And I haven’t seen a way around these issues yet.
There is a feature request thread here, but the prospects of the issues referred to by Brian being resolved seem slim.