Which “online” site are you accessing? The MyCloud.com web portal for remote access? Or the local network http://WDMyCloud for access to the WD My Cloud Dashboard. Next, are you trying to control the backup from a computer to the My Cloud? Or control the My Cloud backup to another My Cloud, USB drive or other local network location (called Safepoint or Backup)?
To configure, control and run the Safepoint / Backup feature of the My Cloud Dashboard, one will need to be on their local network to access the My Cloud Dashboard.
If one is unable to access the My Cloud Dashboard due to not knowing the My Cloud Administrator password, one can reset the My Cloud unit by initiating a 4 second reset via the reset button on the back of the My Cloud.
http://support.wdc.com/KnowledgeBase/answer.aspx?ID=13986
Option A: 4 Second Reset (Reset with Power On)
The 4 Second Reset will reset the following:
•Admin Password (No password by default)
•Network Mode (Default = Dynamic Host Configuration Protocol (DHCP))
NOTE Note: The 4 Second Reset will only reset the Admin Password. It will not reset the Admin User Name. In order to reset the Admin User Name perform Option B - the 40 Second Reset outlined below.