Two of my four Home network PCs have downloaded and installed the latest update (all Win 10 PCs) to NS. After rebooting the two PCs that updated my Laptop disappeared from its own Network Folder and the Network Folders on all the other PCs. In order to resolve the problem I had to use the NRT (Norton Removal Tool) remove and reinstall NS.
The only obvious difference between the two PCs that have updated so far is the Laptop has had the Win 10 Creators Update installed and the Desktop hasn't. My other two PCs that haven't updated Norton yet also have the Win10 Creators update installed. If either one or both have the same problem I'll update this thread.