Two near identical setups; one works, other doesn't

[nickc]

Solved! Feeling rather embarrassed, I should report for the benefit of others that this problem was caused by an oversight of mine, thankfully traced by Simon's indefatigable troubleshooting. Some weeks ago I had been trying out different VPNs and similar setups, one of which had been a service calling itself 'Unlocator' which worked by clients changing the default DNS servers on their machines. I must have tried it on the QNAP and then, when the free trial ran out, completely forgot about it and never changed the DNS settings back to default. Doh!! Simon's diagnostics found that MinimStreamer was failing to get an accurate time signal as it was being rebuffed by the no longer functioning (for my IP) Unlocator DNS servers. As soon as I made that change this morning, the music was happily playing again. Thank you again, Simon!