Did you ever show up one day and one, two or half the computers in the office won’t connect to a share on another computer, server or NAS? Welcome to the wonderful world of technology.
This seems to go in spasms and through different clients. Sometimes it is on a peer-to-peer network, other times it is on a domain. Rarely if ever does it occur on more than one client at a time.
This can happen when backups are to run on an NAS, or to a shared database that has worked fine for years.
What you ten to get is \\sharename not found. Examples are below.