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Destination Host Unreachable

We have a network of about 30 computers.

We have a Server with 3 Virtual Servers. We have a Linksys VPN concentrator,

I do not know if it is a coincidence or not, but following a Windows Update on the Server - This update was performed remotely connecting through our VPN I lost connection and went to the office. The Server was finishing the update and rebooted and everything came up fine on the Server.

However, NO computer on the network can access the Internet and pinging any computer on the network receives a Destination Host Unreachable error from (That is the Gateway address which is the VPN Concentrator).

I can connect remotely to the VPN, but cannot connect to the Server and receive the same error.

No Internet access and none of the computers can ping the server. The Server cannot ping anything but itself (the 3 virtual servers). Nobody can access the Server or the Internet.

I don't see how the Server could be the problem because none of the 30 computers can access the Internet either including the Server. is the gateway address on the VPN Concentrator. Could this be a BAD VPN Concentrator? None of the computers can access the Internet and I don't see how that involves the Server. Again, none of the computers can ping each other - The entire network appears to be broken.

We have 3 network switches that all of the workstations are connected to and the switches are all blinking on and off continuously like collisions are occurring.

Let me also say the Windows Update was occurring remotely on Flash1 which is the Primary Server which contains the 3 Virtual Servers Flash2, 3 and 4. The Domain Controller is Flash2 where the Active Directory is located and DNS. I got disconnected from the network and when I tried to reconnect I connected to the VPN itself, but could not access any of the local servers ( so I went to the office where I discovered that I could no longer access the Internet from the Server or any of the workstations and none of the computers can ping the Server or any other computer on the network.

I have never seen anything like this.

The Primary Server and 3 Virtual Servers via Hyper-V appear to be fine - can ping each other, but nothing else and none of the workstation computers can ping the Servers and the Servers cannot ping anything but itself.

After connecting remotely via the VPN the error :Reply from is OK, but pinging any of the Servers, 19, 21 returns Reply from Destination Host Unreachable occurs when trying to ping. They can only be pinged when sitting in front of the Server itself.

1 Solution
Larry Struckmeyer MVPCommented:
You don't say which device is the DHCP server, but it is probably one of the VMs?

My first response would be to power off everything and bring up one switch, the Host and a station on the switch.  Verify that they are in the same ip subnet and see if you can ping back and forth by IP.  You won't be able to by name until the DNS server is up.

If that works, verify the default gateway and see if either can ping or  If that works, the gateway is working.  Test VM1 in the same way.

If none of this works and all the lights are still blinking on the switch you may have a failind/failed nic or switch/port.  This can be a headache to track down.  Try a different set.
I have seen issues like this related to the MAC address changing on the server or router and then Windows 7 clients flag it as an unknown "Public" network and won't work with it correctly.

Try testing from a single PC and make sure the local network is being detected as a "Work" network.

Also things like this can be caused after upgrades by the Windows firewall on the clients or server. Try turning it off temporarily to see if that helps.
Aaron TomoskySD-WAN SimplifiedCommented:
If you have any link aggregation setup and those configurations got reset then it would be seen as a loop and lock everything up. I'd remove any linkaggregates and see what happens
1. Any server/client updates will have no effect on routers.
2. You lost connection after server updates, means that DHCP/DNS was issued by the server previously. You should check DHCP/DNS  set up on server, see if this changed from previous configs.
3. Check routers configs, there should be no DHCP enabled.
4. Check client machines if they DHCP clients or IP address was statically configured.

There is many other variation can be, but you probably want share connection diagram.
If previous set up was not done by you, and previous person did a lot of "twicks" it can be very difficult put it back together again.
Chuck0410Author Commented:
This whole think turned out to be stupid on my part. I got to looking at device mgr and the NIC cards had an error. I replaced the System board in the Server to no avail. Turned out to be a driver released by HP in April following a Windows Update that screwed everything up - so it was the NIC cards in the Server.
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