What troubleshooting steps have you performed? Can you access the My Cloud using it’s IP address? Have you disabled any third party firewall software and test to see if it can be reached? Does the My Cloud have a static or assigned IP address? Is the My Cloud using the same workgroup name as the computer? Is the My Cloud in the same IP address subnet range as the computer?
If you haven’t already you may want to read through the following post up to Windows 10 Specific Method 5 and ensure various options like NetBIOS over TCP/IP and others are enabled.
https://community.wd.com/t/compilation-of-windows-10-methods-steps-and-solutions/142576
