Shared folder access revokes intermittently

Hello,

I have Hyper v 2012 installed on bare metal.

In guest virtual machine  we have windows server 2012 r2  . we have shared one folder on the disk that is  accessible by 3 other machines.

We get the issue of accessing the folder intermittently. while the folder is not accessible by unc path, it is accessible by IP address only.

We need to access this folder by hostname unc path as it is application requirement .

While this issue happens , the ping & remote response is fine. But onlu shared folder is inaccisible.

Server is patched up last 3 month patches .