Search this subforum for the word “sleep” and you will find numerous discussions on why the My Cloud doesn’t always go into sleep mode or why it constantly wakes up. There is NO firm solution to this sleep problem short of disabling various My Cloud services including the media servers. What works for one person to make their My Cloud sleep may not work for you. Note: The My Cloud is designed to be left on 24/7.
Some past discussion, there are many other threads:
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
