I set up a 2Tb MyCloud with a 2Tb MyPassport via the USB port. Setup went smoothly and my first backups went OK. But like several other posts, both drives stopped responding after a few hours (maybe after going into sleep mode?) and the MyCloud desktop apps would not run.
Pulling the power cord and allowing the drives to restart got them back online, but the problem repeated several times.
I was about to either disable the powersave function or change the DHCP pool and assign a static IP (a task well above my pay grade) when I noticed that the date and time displayed on the MyCloud Dashboard Settings page were way off, like about 3 weeks behind the correct time. Next to "Primary Server" I clicked on "Configure", and the current NTP servers were time.windows.com and pool.ntp.org. Several restarts did not correct the clock. I added time.nist.gov to the server list and saved it. After another restart the clock was correct and both drives have worked perfectly since then, about 5 days now without loss of connection.
I don't know why it worked, but I'm happy. Just a suggestion to take a look at the date/time setting before doing major network surgery.