It looks like it is sleeping but not really

My Cloud OS 3 Personal & Network Attached Storage My Cloud
3

I had lots of disconnet problems.  Count yourself lucky that yours actually woke up, mine did not.  However, if it wakes up that often, the more reason to turn Sleep mode OFF

See my post about disconnects

http://community.wd.com/t5/WD-My-Cloud/Seemingly-random-disconnects/td-p/700668