I sent the Synology back in the end and have just returned all drives to my Lenovo server as even with emby I could not fix the above.
My server will put all hard drives to sleep using 16w when the drives have been spun down and around 25w when spun up and idling. For comparison the Synology was using 21w with all drives awake, but only 7-9w with hard drives spun down (9w standard sleep, 7w some “special” mode.
So the Synology used 16% less power than the Lenovo when awake and 43% less when asleep...
Were you not able to shutdown and restart either of the media server apps simply using the scheduler?
I already owned the Lenovo, thus that was a sunken cost (not only a quarter of the price of the Synology too I may add). The Synology on the other hand was £460 and wasn't going to give me anything more unless it could save energy

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The problem with a scheduled task was it would end the utility of the device making life more difficult as I want the Synology to sleep for the majority of the day when it's not being used. I'd have to have a different schedule for each day and then risk on certain points of the day where I might decide to watch something that the service isn't available. Shutting down just at night would still mean many hours in the day it using more power than it should be doing.