Understanding UNC Paths and IP Address Resolution
First, please be aware that when Windows won't resolve a computer name, it is still possible to access a system using an IP address directly providing the systems are on the same subnet and the Firewall allows it (which is in 99% of most cases where it worked before but no longer does).
For example, Steve's PC name is "Steves-PC" and his laptop name is "Laptop". When an UNC path (Universal Naming Convention path) resolves properly, typing in \\steves-pc into File Explorer will resolve the computer name to an IP address, and the same for any other machine on the network. Services such as Remote Desktop Protocol (RDP) use the same method to resolve computer names.
However, if the name resolution is broken, then things stop working. One way around this is to look at the IP address of each system and access it using the IP address. So, \\steves-pc might resolve to 192.168.0.5, which can be entered in as \\192.168.0.5 in File Explorer and Remote Desktop.
You can find out which IP is assigned to each PC by clicking Start, then type in "CMD";' wait for "CMD.EXE" or "Command Prompt" to appear, click it, then type in "ipconfig" and press Enter. The IP address of the computer will be revealed.
That said, this IP addresses in this manner is not convenient, and IP addresses on the network can change. But in an "emergency" situation when you just want it to work, an IP address is a quick way out.
Microsoft recommends setting a list of services on all your PCs as "Automatic (Delayed)" to help with the name resolution. In most cases this should resolve the issue, but in certain cases it may not work (such as with OpenVPN - I will describe a second method in a future post).
To do so:
- Click Start, then type in "services.msc" and press Enter. The "Services" Window should now appear.
- Scroll through the list of services, then double click "Function Discovery Provider Host (FDPHost)"; this will bring up a new window. Next to the heading "Service Status" it should say "Running"; if it is not, then click the "Start" button. Above that, set the "Startup type" to "Automatic (Delayed)".
- Do the same for the following services: Function Discovery Resource Publication (FDResPub), Network Connections (NetMan), UPnP Device Host (UPnPHost), Peer Name Resolution Protocol (PNRPSvc), Peer Networking Grouping (P2PSvc), and Peer Networking Identity Manager (P2PIMSvc).
- Repeat the same procedure for all PCs on the network.
- When the changes have been made, reboot all PCs.
- Finally, attempt to access your systems over the network using an UNC path using File Explorer.
In my testing, starting the first three services in the list: Function Discovery Provider Host (FDPHost), Function Discovery Resource Publication (FDResPub), and Network Connections (NetMan) made the Remote Desktop Protocol (RDP) and File Explorer resolve the computer names.
I hope that helps!