Cannot access network resources of just one Windows 7 PC

I have been working a lot into this problem and I would like to get suggestions on how to investigate further. This is the situation: I am working on the IT infrastructure of a small office (15 computers). This is what they have:

• 14 Windows 7 PCs
• 1 Windows 10 PC
• 1 NAS
• No Windows server and No Active Directory

Each PC has a shared folder that should be able from all other PCs. Who set up the network didn't put a Windows Server, but each PC has that folder shared with R/W permissions to "Everyone" (avoid insults for security, I agree with you ... awful job, but I cannot change it). Each PC has a name of type UTXX where XX is the number of the computer (01, 02, etc).

If I click on "Network", I can see UT01, UT02, etc. When I click on UT01, for example, I can see all the shared folders, access and edit files inside... Except for UT03, for which I got the error 0x80070035

I have worked for 2 days to figure out what can be the cause, reading all the possible related topics. I have also reinstalled the computer from zero but when I install the block of software needed for their work, it stops working. I understand that there's a software changing something but I have no idea what. From UT03 I can see all the other computers and, of course, UT03 too. From another computer (ex. UT02) I can see all other computers as well as UT03 too, but when I click on it ... the error is fired and I cannot see the shared folders.

Just to give you more details, I have tried to:

• Disable the firewall (Windows Firewall)
• Remove the Antivirus (they have Microsoft one)
• Make sure the network set up is exactly the same as the one of the other PCs, like "Activate
• I can PING that PC using its network name (UT03)
• Access directly the folder (\UT03\User) but it doesn't work
• The software kit is just one huge package. I tried to uninstalled the software one at time but, even after removing them all, the problem is still there

What I would like to ask you is: what you would suggest to do now to figure out what's blocking the other PCs from seeing the shared resources of UT03?

I had the same error with several PCs in my network. I could not open shared folders of these PCs with the computer name. It was ok when I write the IP address.

Finally I just deselected TCP/IPv6 checkbox on the connection properties and its all ok.