Yamaha Musiccast feat. Synology DS418 woes (slowness)

[s_k]

Until two years back I used a Yamaha WXAD10 for streaming. It streamed hi-res files (vinyl rips, 24/192) from my Synology NAS. Not an issue. Great.
I upgraded it to a Cambridge CXN. Lovely sounding thing, but the software wasn't too reliable and I got fed up with it. Decided to go for convenience and bought the Yamaha WXC50.
Set it up, expecting it to be as flawless as the WXAD10, only to find that it took about 10 seconds to load from track to track. Sent it back, used a RBP with Voumio, which was quick but buggy, and after that a Windows PC with MusicBee which actually worked really well, while on the lookout for another WXAD10 because 'sod it, that worked fine'. 
WXAD10 comes in. Same issue as the WXC50. Super slow to load tracks, even if you just have it playing it puts 60-10 second breaks between tracks, loads file lists slowly, loads albumart slowly. 
A friend uses the same streamer with a much older DS214 and that works perfectly. 
Does anyone recognize these issues? What I can derive from this is that the problem only appears to rear its ugly head when using Yamaha musiccast devices. The same music server ran smoothly with volumio, windows 10 and whatever the Cambridge CXN runs.
Halp?

[s_k]

Oh, an update already. I removed every folder but one and reinstalled Synology's Media Server. One of those two things did the trick. Going to add folders now, see what happens...

[s_k]

All right. Note to self, and to anyone else; Reïnstall media server first... I apparently had a bit too much confidence in DSM ;).