Since the setup works fine using my Denon AVR, I think I have eliminated the network as part of the problem. The wireless station has multicast routing and IGMP snooping enabled, that was the first thing I was told to try. I use the HEOS app on iOS 9.3 devices connected to an apple extreme base station which is connected to the latest version of MinimServer for Arm on a DS411 Synology NAS running DSM 6.0. To recap, I can get the server to show up, it is when I try to list contents that the 'no media' message pops up. Denon keeps telling me that HEOS needs a DLNA 'certified' server while the Denon AVR is more forgiving and wash their hands of the issue so is there any setting in MinimServer or MinimWatch that I can change to make it work? My Denon AVR on the other hand works perfectly and I can choose playlists and music from MinimServer with no issues. If, on the other hand, I use the media server that comes with my Synology NAS everything behaves as expected with no issues at all.

The MinimServer shows up every time in the list of media servers, no issue there, but the contents will at first refuse to do so with 'no media' showing up until, after several frustrating tries, I finally get through. After that, songs play fine until I try to switch playlists and the whole thing starts again. When using my HEOS app and browsing my NAS based MinimServer, I keep getting “no media” for several tries before getting a listing, then the same thing happens when trying to choose a playlist and so on until I get songs to play.

Music servers not listed on heos app