Beroli, viewed with a texteditor my *.m3u files has this structure on the iMac. If your using a NAS, I suppose the readable directory structure would be different from the OSX example beneath: /Users/Music/Classic Rock/Artist/Album/song.xxx
I guess this will be a question for an owner of Synology Nas's to find out how to fill in the correct directory structure in the m3u file to get it readable on the Moment. In a quick search on the net using a phrase "Synology drive/folder structure", I found it has to be looking like this: M:\Music\Classic Rock\Artist\Album\song.xxx
Secondly, how did you create your playlist from your Nas, with VLC, Foobar, WMP... Is it pointed correctly with the software you have been used?
If you have a correctly pointed m3u playlist and the Moment is still not finding it, could it be a problem of not using Twonky on the Nas? Here you find install files for Twonky on your Nas: