ColdFlame,
Microsoft makes a great utility that you should start with: Netdiag.
I think it comes with the support tools on the Windows Server CD. However, given the results you're getting, it's probably going to say something's broken. You'll probably need to run these tests anyway.
First, verify that a user's machine in SideD can ping the server and that the server can ping the user's machine. With that out of the way, check for any differences in the network setup between the clients at SideD and the server. Maybe there's a different default gateway in use by the clients. Also check for VPN tunnels, Firewall settings, IPSec filters or things like that on the server at SideD.
(if you know how to open a command window, just skip the next part)
Open a command window by clicking start -> run -> type "cmd" and press return.
type the command "route print" - you should see results like:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 10.1.13.140 10.1.13.140 1
First, make sure you *have* a default gateway, and that it's correct. This is the network entry that looks like "0.0.0.0" in the list. If you do, then what you're looking for next is the very bottom of the screen. You want to check for persistent routes. Perhaps a previous tech put in a static route trying to diagnose a problem or during the setup of the WAN. Compare your results with a client PC. Maybe there are static routes assigned in the login script and the server doesn't run login scripts, or the clients pick up something from DHCP that you need to do manually. Anyway, the fact that your clients at that site can ping you but not the server makes the server's networking stack a likely culprit.
For detailed network info, run "ipconfig /all" from a command prompt. Compare the clients' settings to the server.
If there are no static routes, and the client networking settings match your own, do your ping tests again but this time also perform this test (Traceroute):
C:\>tracert
Tracing route to
[64.233.167.99]
over a maximum of 30 hops:
If you can ping the Internet, that's a good sign. Then, run "tracert siteB" where siteb is the router or server across the WAN (use the IP, not the name). Since you know the steps that each packet *should* take when getting to the other side, you should be able to spot the problem quickly.
If your packets get to the router ok but then get stuck and time out, or get stuck in a loop, then the router itself needs to be looked at. This is very unlikely, but still a possibility. It's always possible someone put in a firewall rule on the router that only applies to the server. Hey, it could happen.
I hope this helps, I probably haven't covered everything. I hope some other folks monitoring this page can help fill in the gaps.
Once everything is up and running, here are some free neat tools to help keep tabs on your WAN:
Also this one for monitoring up/down status, bandwidth and errors:
This one has some pretty good SNMP capabilities.
There's bound to be lots more out there too!