I agree that there should not be reliability issues with the Lumin app, assuming a good network (wired or strong wifi); trying to stream hi-res audio over slow wifi can be tricky.
A minor clarification to what rodrigaj wrote: you need a server on the NAS. MinimServer is a great for people who want maximum control of what is displayed in the control point, probably using metadata beyond the typical album/artist/song title information. (I use MinimSever myself and love it.) But it’s a bit harder to set up; if one doesn’t need that level of control, other servers will do just fine. Since randyhat already owns a Synology, he could use Synology’s own Audio Station server along with BubbleUPnP Server and the Lumin control point (for the differences between a true server and BubbleUPnP Server, see post #15 above).