I can't access My Cloud on my home network. Help please!

That is unfortunate - I have found the WD MyCloud to be very good network storage. I did make some advanced changes to make it work better with Macs, but they are not required to see the device on your network. https://community.wd.com/t/solved-tweaking-samba-smb2-for-mac-androids/236189

I am surprised your Virgin help desk could not help with DHCP range settings. I assume you are in Europe and it is a combination router/modem.