Synology

[simoncn]

I think you said that it only happens when you stream from the NAS by wi-fi, not when you stream from the NAS by Ethernet. This would indicate that the issue is related in some way to wi-fi.

MinimServer streams the audio data across the network to the Aries, so it is "played" by the Aries in both cases.

Your Mac mini is a more powerful machine that the NAS. If the wi-fi connection is marginal with respect to throughput, driving it from a slower machine is more likely to show up any issues.

Sometimes switching from a 2.4 GHz to 5 GHz wi-fi connection (or vice versa) can improve performance. It might be worth trying this.