Came across an issue on a Windows 2008 R2 server which when browsing the network it was only discovering half a dozen PCs, none of the other servers were discovered. Even if you typed in the UNC path of the other servers i.e. \\server1 it still said it was unable to find it. Stranger still you could ping other servers and PCs by their names and these resolved to the correct IP address and received a response.
A quick check discovered that the Windows Firewall was off and not blocking this and the next thought was network discovery wasn’t turned on, you can check that here:
Start > Control Panel > Network and Sharing Center > Change advance sharing settings
Network discovery > Turn on network discovery
Although in this instance network discovery was turned on it required more digging to which I found that you weren’t able to either access any of the mapped drives. Why only this server wasn’t able to see the other systems on the network as well as access their UNC path.
The next place I checked was the network cards advance settings which gave me the answer to this little mystery, to check the NIC’s advance settings you go here:
Start > Control Panel > Network and Sharing Center > Change adapter settings
Select your NIC and then is the menu toolbar isn’t showing press the ‘ALT’ key and select:
Advanced > Advance Settings …
This was what I saw:
The tab for ‘Provider Order’ was missing, gone! This would mean there is only one provider listed which shouldn’t be the case and what is likely to be causing the problem, to see what providers are listed you need to go here:
Regedit > HKEY_LOCAL_MACHINE > SYSTEM > CurrentControlSet > Control > NetworkProvider > Order > Sting Value ‘ProviderOrder’
You can see only one provider was listed, PDVFSNP which belongs to Symantec Backup Exec which was installed on the server, maybe during the install it lost or kicked out the other entries which should be here, tut tut Symantec! The main issue here is we are missing the RDPNP and LanmanWorkstation provider, this is the key to our problem. After I checked a couple of other servers which are setup the same I was able to identify which providers were missing from this key and which order they should be in. They were as follows:
*Of course whenever your making changes to the registry please make a backup!
Once I had entered these additional providers into the key I went back to the NICs advanced settings and hey presto the ‘Provider Order’ tab was back :
Now back to Windows Explorer and clicking on a mapped drive didn’t bring back an error it displayed the files and folders held within, marvelous! Browsed the network and after a few moments shazam over 30 different PCs and servers were listed and double clicking on a system opened up it’s shared folders, jobs a good’un
A good little tip if the obvious things haven’t worked.