I just got an update for Windows 10 and lucky me I can no longer see My Cloud or My Cloud Mirror under Network/Computer in File Explorer. Yay Microsoft! They both still show up under Storage but that just launches the Dashboard. I tried most of the proposed solutions of AllowInsercureGuest, IPV4 use netbios, public-private network, allow network discovery, blah blah blah. Nothing worked.
Luckily I could still get to the boxes typing the UNC name in File Explorer. However every time I closed File explorer it was gone again. If you can get to your MC by typing \MyCloudName\ in the file explorer address bar do this:
Open File Explorer
In the address bar type ‘\MyCloud’ [enter]
(obviously use the name of your cloud including spaces)
When your My Cloud shows up in the left pane under Network right click on it
Select ‘Pin to Quick access’
Curse Microsoft and swear about how stupid it is you had to do this
Your MC should now show up under Quick Access in File Explorer and in my case it survives a reboot. Not sure what issues you may have with third party apps if you want to get to your MC but it seems to work OK. Hopefully MS will come up with a fix that doesn’t require us to force MC to use SMB1.