Try these solutions:
1. Ensure your chosen UPnP server software can serve the file type you are trying to access. Some servers do not serve FLAC for instance
2. Make sure that you are using non-DRM files
The EDGE NQ can only play non-DRM files. Files that have DRM controls cannot be played by the EDGE NQ. Some servers may be able to authorise and de-crypt Microsoft Playsforsure before then serving the content to the EDGE NQ but this operation is not guaranteed as it is purely a function of the server.
3. If attempting to play 24-bit WAV or FLAC content note a wired Ethernet connection is normally required for reliable operation due to bandwidth considerations
4. Check the EDGE NQ can play back the file type you are trying to access
Supported file types: ALAC, WAV, FLAC, AIFF, DSF and DFF containing DSD64 at 2.8224 MHz or DSD128 at 5.6448 MHz, WMA, MP3, AAC, HE AAC, AAC+ and OGG Vorbis.