Thanks Blackjack and apologies for my brevity. Post COVID lockdown in Sydney Australia, I had two mates round for a few drinks and to show off Roon…suffice to say my demo was less than successful 
Anyway my setup is on a Synology NAS using the docker solution describer here
I haven’t got around to upgrading to DSM 7.0 yet so that might be an issue.
Apparently LINUX isn’t an issue for Synology NAS.
In the meantime I’ve setup a core on my PC which is working fine and I may forgo all the effort involved in doing it via a NAS.