Try to do a reset on the unit bu pressing the hole shaped button on top of the ether net on the back of the drive and see if this helps you out. You can also try to see if the dashboard is accessible from a different computer on your network.
Here is a link that might help you with he reset process:
Interested to see what your resolution was - as I seem to have the same problem. Also, what do you think about the Apple Airport Time Capsule instead of the MyCloud?
Go back to the computer that you can access the Dashboard with and check the address, write it down, then go to the computer that is not showing it and use that address to see if it will open. See example image below.