Agreed it would seem the connection to the NAS is the prime suspect, which would also heavily implicate the R7000 router. I have therefore taken the opportunity to upgrade my Internet connection to the latest 4GEE modem/router, which also offers me the option to remove the Netgear Nighthawk R7000 router completely and replace it’s connectivity with my switches.
Current status is that stoppages appear to have ceased with the core on the NUC and storage on the NAS.
Stoppages immediately return, however, if the core is re-located to the NAS.
Conclusion: Roon does not like the core to be installed on a Qnap TS 251+ NAS, but is happy for storage to be located there.
Please note I remain unconvinced that this is a specification issue due to the lack of evidence of any strain on the NAS. I would suggest you take a look at the Qnap Server version of the core for issues?
Kind regards
Nick