I have had nothing but problems with the Mycloud. Slow, disconnects, cant see a backup drive my book connected to it. May have something to do with the firmware. I am about to throw this thing in the garbage (return for a full refund) if this thing continues to work this way.
How is your My Cloud connected to your router? What type of router do you have? What computer are you using? Have you looked at the User Manual?
Mate before you do that, ensure you upgrade to the newest firmware.
Prehaps in the store they sold you one with old firmware having lots of issues, give it a try before you return it.