I needed to have access on a branch PC on another subnet ( from the main site’s subnet ( 

Using remote desktop, I turned off Windows Firewall on the PC and could access the C$ share on the remote PC from the main subnet. 

Looking at the Windows Firewall exceptions, I could see that File and Printer Sharing was already checked.  I clicked edit and saw the required ports defined here.  When I clicked “Change Scope”, I saw that it was set to “My network (subnet) only”.  For all four entries, I changed the scope to use a custom list that encompassed all 192.168.x.x networks and was able to browse the C$ share from all subnets. [more]