Destination host unavailable...But card is receiving and sending packets :S

[WarDwarf1980]

Hi Everyone

Heres a stumper maybe :S

I am running a wsus server on windows server 2003.
A couple days ago the connection to the server dropped.(For no reason, just this one machine lost connection) So I start investigating. I see that ALL other machines on the network are working fine, so the problem is isolated to this one server.

A ping to the gateway gives a "destination host unreachable" error.In fact a ping to ANY other machine gives that error.

ping localhost works fine. As does ping "server IP (Same thing I know, was just covering my bases ). I change Cat5 cables with a working machine and same prob, and cable from wsus server works on other machine, so its not that.

I check to see if lan is enabled...it is.

I check network properties and it says "connected"
I also notice it is receiving packets and sending packets....not much but it is going up.

Full virus scan with Symantec Endpoint protection reveals no malicious software.

Then I thought ok ...onboard NIC in its chops. So I take HDD out put it in a completely other machine , install drivers for that onbaord nic, and set up the network IP's and DNS's and Gateway again.

SAME PROBLEM !!! Now I'm stumped? All Ip's Dns's and Gateways are correct...I dunno what to do and am not in mood to rebuild my wsus server.

Please help oh wondrous technical IT people of Tech Support Forums

[WarDwarf1980]

Its ok guys , solved the problem.

I noticed in event viewer that a service called IPsec entered block mode.
This service handles something to do with inbound AND outbound TCP/IP traffic. When in block mode, it doesn't allow any TCP traffic through except some security traffic (hence the packets I was sending and receiving). So you find that the NIC is still operational and connected but connot ping anything.

I stopped the service completely and all network activity resumed.
I do not know why the service entered block mode but , yeah, thats how I solved it.