To recap:
When using Windows Explorer on the PC, the MyCloud HDs (including a USB 3.0 connected WD Passport 1TB) are treated like any other HD on my PC. On the laptop, not so much. There, when I try to bring up the MyCloud, I get a "Windows cannot ACCESS \\XXXXMYCLOUD" message.
Could the fact that the PC is hardwired (ethernet) and the laptop is on WiFi have anyhting to do with this?