Use the following command on Terminal to SSH from a macOS 10.12 (Sierra) computer to a My Cloud:

1. Double-click on the Mac HD, the internal Mac hard drive visible on the top-right corner of the desktop screen.
2. Click on Applications.
3. Click on Utilities.
4. Double-click on Disk Utility.
5. In Disk Utility, double-click on Terminal.
6. In Terminal, type the following command:

ssh -oHostKeyAlgorithms=+ssh-dss sshd@wdmycloud.com.local 

Note:

If the device name has changed, please use the IP address of the My Cloud instead.

Thanks to Source