There are numerous threads discussing the sleep issue with the My Cloud units that can be found via a forum search. For what ever reason with the basic settings active, including the Twonky/DLNA media server, the My Cloud just doesn’t sleep for long periods of time. For mine it goes 8-10 minutes before it wakes up again. There are various things one can try via SSH to turn off services and perform other actions that helps more or less to let the My Cloud sleep for longer periods of time.
Here are just a few recent threads discussing the sleep issue and possible things to try to deal with the issue:
https://community.wd.com/t/mycloud-does-not-go-to-sleep-standby-perhaps-the-solution/158591
https://community.wd.com/t/this-resolved-my-cloud-sleep-mode-issue/157059
https://community.wd.com/t/new-sleep-awk/153431
There are many others.
