I have found a workaround for my problem with the new firmware of mapping shares to Windows Vista drive letters.
With the new firmware release Windows Vista cannot see any Share on my WDMyCloud NAS without the Share being Public. Once made Public you still need of course the correct User name and Password to read or write to the Share.
Under the last firmware Windows could see all the Shares on the NAS as a network drive and could access if you had at least Read access and were the correct User with correct password. Or if you were the Admin account with correct access and password.
The downside/problem that needs to be fixed is: By me making the Shares, I need to manage, Public all my Users offsite using the WD My Cloud Mobile App or WD My Cloud Desktop App can see and read the Public Shares. As I have several offsite Users I don’t want them seeing everything. This makes the device not fit for purpose.
Being able to see Shares as network drives under Windows, needs to be put back to how it used to work under the previous release where from my usage all worked correctly. Of course Windows should only be able to access if you have the correct User and Password. At the moment you cannot see the network drive to be able to access it.
Hope this makes sense and WD are reading these forums.
PS I have also tested on my Android Samsung Galaxy S4 and have exactly the same issues as Windows Vista. Have also tested on iPad2 IOS7 with Goodreader and FileBrowser , they all cannot see when on the same network my NAS Shares as LAN drives unless they are made Public. They used to be able to see then but not access unless they had the correct access rights.
PSS I have tried twice to roll back the Firmware to a previous version with my WDMyCloud not allowing me to do so. This is equally a big issue that needs to be fixed, Can WD post all versions of Firmware releases on their website and test that we users can download and install to upgrade(which appears to work) and downgrade when necessary. My automatic update of Firmware is now permanently OFF.
Update 11 Feb 2014
Talked to WD Support and have solved my problems.
The firmware update appears to have corrupted my User Passwords.
I had to do the following through the WD My Cloud Dashboard.
1 Refresh all User Passwords. By selecting each User then edit by the side of password and entering a new password.
2 Switch off the Public access for each User I had been forced to give to my Shares
3 Reinstate the access I wanted each User to have to each Share i.e. Read, Read/Write etc.
Then in Windows Vista I could Map Network Drives for each Share on the WDMyCLoud NAS as I had before.
Note: Some of the shares would not appear straight away. I had to go back to the Dashboard make them Public then switch Public off and reinstate the Access rights again for each user. After several attempts it worked.
WD Support also requested I make the WDMyCloud IP address static, which I did via my router. Apparently this makes the device more stable.
Also to roll back Firmware you need to make the file a higher number as SectionGZ suggested.
WD Support were very knowledgeable and helpful.