Access intermittent

I have a new network and my WD Cloud is hard wired (lan) into my Router.
I have been trying to download a directory of files using explorer and most will read fine, but several are not accessible. It is like the drive goes off line.
When I try to access the drive via my cloud website, I see the files / directory but I can not download.

Win 7 Home Premium, Firefox 59.0.2 (64 Bit)
( I cannot even see the device in my network list on Win 10 laptop and same error trying to download from web)
Thanks in Advance! Kathy

I don’t know what the problem is with Windows 7 but look at this for Windows 10 and getting it to show.

Where does Firefox come into this?

If you are local to your network, use File manager, and map shares as network drives, mapping all shares with the same MyCloud user credentials.

Thank you so much for finding that for me. I suspected it was a network thing and I get very lost trying to troubleshoot anything network. Yes, it did allow access.
Again, a thousand thanks! Kathy