Nserve and Minimserver - intermittently failing to find music?

Just wondering if anyone else has found this and if there's a way around it...

Using a Synology 213 with Minimserver transcoding flac to wav, I sometimes select a song or album and "connecting" appears on the NDX's display for a while before eventually it just reverts to the stopped screen.

This doesn't happen with particular albums all the time. In other words, sometimes a particular album will work, sometimes it won't. Equally, even when N serve on the iPad won't get it working, I can use the front keys on the MDX to navigate to it and it will work fine.

Does anyone know what this problem is and if there's anything I can do about it. It isn't happening often enough to be a disaster, but it's annoying and I'd also like to sort it out if possible.

Many thanks in advance