I have a situation whereby there are 3 sites.
Site a - User site
Site b - User site
Site c - datacentre
Site a can talk to site c fine Site b can not talk to everything in site C
In particular, workstations in site b are struggling to communicate properly with site c. For example - there are servers that we can ping, tracert, even telnet on port 80 (or other app ports) to but cannot for example browse network shares on them. Microsoft Network Monitor shows connections are made during these attempts, but I cannot browse and get the following message:
"\\server\share" is not accessible. You might not have permissions to use this network resource. Contact the admin of this server to find out if you have access permissions. The specific network name is no longer available.
The server is available and I do have access. I can access without issue from Site A.
Where should I start looking?
My first guess, without further info, is that the connection between B and C is not fully transparent.
Can you RDP to a server in C (either from A or B) ? Then do some ping and tracert tests from C to B and see it that works.
If that doesn't work you most likely have a routing issue from C to B.
If it does work the base connectivity is there in both directions. In that case the culprit is most likely some firewall/filter between B and C that kills some protocols (SMB/CIFS).
As Bart already stated: Without more details it hard to be more specific.