Can't access NAS by its name in the network after 6.10 upgrade

Before the 6.10 upgrade I was able to access all our shares simply by accessing \\NAS01. After the update, none of our Windows PCs was able to open the location, receiveing a Windows Explorer error stating that the network location could not be found, or no permission existed.

Replacing NAS01 with the IP address worked without problems, so it wasn't a newtork or SMB issue.

What I discovered was that if I changed the NAS's name to say, NAS02, it would reappear on the network and everyone was able to access it. No login promtps or error. I changed it back as I have tons of shortcuts everywhere on the network pointing to the old name.

All our NAS accounts are local, but they match those from everyone's domain account on their PCs. This allowed us to access the NAS without any login prompt whatsoever. 

After endlessly trying to figure out the problem, I added a Windows credential through Credential Manager in Control Panel with the \\NAS01\username nomenclature and I was able to instantly access the NAS with the old, original name. 

I'm instructing all our users to do the same and add their credentials, but this does not really answer my initial concern: Why was I able to access the NAS by changing its name without having to create credentials in the first place, but had to create one to access it with the old name? Is there some sort of caching in Windows (or the NAS itself) that got corrupted after the upgrade?

I never had to create credentials before, or having to login to the NAS from Windows Explorer for that matter.  Since the NAS local accounts match the Windows login credentials, there was no need to. Everything worked as if it were SSO.