The specified network name is no longer avaiiable

I have been using WD MYCLOUD for many months on my PC (Win 7 Family Premium 64-bit) and my android devices without any problems whatsoever. I haven’t used remote access at any time. Suddenly over the weekend I experienced several error messages - WD MYCLOUD not available or not accessible on both Windows Explorer and the WD Interfaces. Here is a screen capture of the latest error message and any assistance or advice would be very much appreciated. 

WDMYCLOUD 01.PNG

The most frequent cause of this sort of problem is that your router has decided to re-assign the IP for your MyCloud*.

Shut down the browser tab.

Use your router’s UI to find the IP address assigned to the MyCloud, then tell the router to always use this address.

Then open a new browser window, and enter the URL /UI.

* this can happen if your router or MyCloud reboot, or if your MyCloud decides to do a firmware upgrade.

Thank you for your quick response and advice. I have checked and the IP address assigned by my router to WDMYCLOUD and the IP address shown on the WD MYCLOUD interface are both the same. 

Last night I tried  on several occassions copying a few files from WDMYCLOUD to my PC Hard Drive using Windows Explorer. The first 3 or 4 files copied no problem but the next file got as far as 60% then it stopped and an error message appeared stating WDMYCLOUD was not available and to check my network connection. My PC and WDMYCLOUD are both connected to my router by network cable and my internet connection is first class. 

Any furher advice or assistance would be very much appreciated.