My Windows Server 2003 has two NICs, one for LAN and the other for dedicated Internet access. Suddenly, the Internet connection stopped working. It can ping itself and the hosts on the LAN. However, it can't ping any Internet address or its own DNS. Both NICs are set to static IPs and IP routing is enabled.

Sometimes, if I disconnect the Internet NIC's Ethernet cable and reconnect it, I can briefly access the Internet, but it disconnects shortly afterwards. If I connect the same Ethernet cable into another machine and set the IP and gateway correctly I'm able to normally connect to the Internet.

The Server was working with the same configuration before and no alterations were made. I've tried restarting the server and the routing service to no avail.

UPDATE: I connected the Ethernet cable into another machine, configured it and Internet access was normal. After that, I reconnected the cable into the Windows server, but this time, no problem happened. The Internet access is normal and it is routing traffic to/from its hosts. What could have caused the sudden loss of connection on the first time?

  • IP routing is enabled - What does that mean exactly? You don't have to explicitly enable routing on a Windows OS, so I'm not sure what you mean by that. Also, give us some more details. When the problem occurs are you able to ping the default gateway? Does DNS resolution work? Etc., etc. Also, do you have a default gateway configured ONLY on the internet connected NIC? You should. A Windows OS can have only 1 default gateway. – joeqwerty Oct 9 '14 at 23:22
  • By IP routing is enabled I mean that the Routing and Remote Access (RRAS) service is enabled. I do have only one default gateway configured and it is on the Internet NIC. – Vin Oct 13 '14 at 14:26

You probably have a route problem.

As soon as you lose internet connection, run route print to see if your default gateway is pointing to the right address. Probably it will be pointing to a server on your LAN, and not the right server.

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