Windows 10 client blocking access to server open file share with guest access

A new policy implementation on a new Windows 10 machine can cause Windows 10 to report that certain shares are inaccessable due to policy settings.

The solution is to change the Local Group Policy with gpedit.msc:

Navigate to Computer Configuration -> Administrative Templates -> Network -> Lanman Workstation and select the Enable insecure guest logons as shown in the below screenshot.