Windows 7/SBS 2003 Networking Issue complicated by Verizon Router

Question

I posted on Answers.Microsoft.com ( http://answers.microsoft.com/en-us/windows/forum/windows_7-networking/windows-7-suddenly-wont-talk-to-sbs-2003-server/e8116774-6b4f-44d3-91cf-b10df236805a?tm=1405553282721 ) and here at TechNet in the Windows 7 IT Pro
forum ( http://social.technet.microsoft.com/Forums/en-US/1f8b8cbc-4b9d-4f68-981c-4c71e7a3f24a/windows-7-suddenly-wont-talk-to-sbs-2003-server-and-viceversa-possibly-dns-but-not-definite?forum=w7itpronetworking ) a problem that I was having with our Windows
7 computers suddenly losing connectivity to our SBS 2003 server. Someone posted an answer (rebooting our router), which worked, but only on a temporary basis. After turning off the router and turning it back on, we get connectivity back for about 3 days, then
we lose it again, and we have to reboot the router again.
I called Verizon, and the tech I spoke to claims that the problem is that the SBS 2003 server should not be the DNS and DHCP server for the network - the Verizon router should be. He's claiming that the fact that we have IP Address Distribution turned off
on their router means that the router never properly knows where each address is assigned. The fact that this all worked up until a week or so ago, and that it's only the Windows 7 machines that are affected, he doesn't have an answer for.
His suggestions were either A) turn off DNS and DHCP on the SBS 2003 server and have both run through the Verizon router, or B) assign static IP addresses to each machine. From what little I know (I inherited this system from someone who left little or nothing
in the way of technical notes) DNS and DHCP have to be running on the SBS 2003 server since it is a domain controller. B) seems possible, as long as I note the static addresses both on the server and on the router.
This still, however, does not really address the underlying issue. Somehow, I think there should be another, easier way to make this work. Especially since, as I said, these Windows 7 machines were content to run for about a year, and only in the past week
or two started having this issue.
Any help would be greatly appreciated.
============== Brian Gerstel Billing and IT Support, Regional Bankruptcy Center of Southeastern PA, P.C.

Answer 1

The LAN is all one subnet (it's not a very big office), a 192.168.1.X network.
I don't think the router's firmware has been updated recently, although I can't swear to what Verizon might have done "behind my back" (they do funny things with some of their routers, from what I can tell),
The router doesn't sit between the server and the clients - it only links our LAN and WAN (there's 1 port on the router hooked to the uplink port of a 16-port Gigabit switch which handles the LAN).
The router is the default gateway for all the systems on the LAN.
When the Windows 7 problem occurs, a Windows XP client can ping a Windows 7 client and vice versa, but a Windows 7 client can't ping the SBS server nor vice versa (and in all cases, I'm pinging numeric IP addresses, not the name). Since the SBS server is
the DNS server, the Windows 7 clients effectively lose the ability to go out on the Internet, although some programs that must cache the data (like Microsoft Outlook) seem to continue working so I think WAN access is still up for them.
Brian Gerstel Billing and IT Support, Regional Bankruptcy Center of Southeastern PA, P.C.