Thanks for your reply Dylan. I do not think the Synology is the issue. I have a relatively small library ~ 850 albums. I will try and install the core to an SSD conected to the synology, but I wil have to wait a couple of days for that.
I am inclined to say it is a software issue instead of hardware after reading these posts:
I have tried what seem to work for others (i.e. deleting the cache, but the problem persists).
I have also tried to stream Tidal from my Mac (within Roon of course), and I get the same result: nothing plays, tracks are just skipped.