Server Loses Network Connectivity

The Server loses all external network connectivity.
No new or unusual errors present in the EventViewer logs.
The computer remains accessible through the KVM (Keyboard Video Mouse), normal user interface.
I can ping
I cannot ping beyond that, not even to the switch.
Changing ports on the switch does not help.
The remedy has always only been to reboot.
The NIC settings are such that power management is unchecked.
Dell replaced the MB which contains the NICs,, but that did not help.
I added an intel NIC, but that didn't help.
This is SBS 2011.
It happens once or twice a month, or once or twice a week, sometimes each day of the week and it happens any time of the day or night.

It is on a PowerEdge R320.

Do you have any ideas of what is happening?
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David Johnson, CD, MVPOwnerCommented:
Broadcom® 5720 Dual Port 1Gb LOM -- switch this out and use only intel nics broadcom drivers lately have been really flakey

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awed1Author Commented:
Thank you for the input.
For a while I thought that was the trouble, but I have already changed NICs to an Intel NIC, because someone's post online said that it had to do with Broadcom, but the problem remains. Is there some way it could still be using problematic Broadcom drivers - I don't know, perhaps through OpenManage or something from Dell?
David AtkinTechnical DirectorCommented:

Open the SBS Console>Netwokring Tab>Connectivity sub tab
Run the 'Fix My Network' Wizard from the right hand side.  report back on any warnings/errors.

Also, download and installed the SBS Best Practice Analyser and run a scan.

When the problem occurs, does disabling and re-enabling the NIC do anything?
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awed1Author Commented:

I appreciate your suggestions. Yes, I have run the "Fix My Network" wizard quite a bit. It usually tells me a list of errors. Some of them, like "A Networking Component is not configured Properly" it fixes - or says it does, but some it leaves up to me - like "DNS is using a DNS Forwarder" &  "Could Not Configure the Router." These are okay with me because we seem to need the forwarder and the router is not under the control of the SBS.  It also tells me that there is an error while trying to connect to the Exchange Management Shell. That is not set up to take the kind of connection it is looking for. So I leave it.
I have also downloaded and run the BPA, a few times, but I don't remember the end result. I guess I could look at it again, but I think I have, in the past, not found anything useful in it.
If, when the problem occurs, I disable the NIC, it takes so long to re-enable it, if it does at all before the almost inevitable reboot, that I start thinking about looking for another job because I feel like I-have-as-good-as-lost-mine.

What I am in the process of doing:
I have installed an older Intel NIC which often gives me several days of operation before the  failure (The, embedded in the MB, Broadcom NIC often failed daily).
The Intel NIC is not on the hardware compatibility list for the server, so I have bought another Intel NIC that is the right model, and am looking for an opportunity to install it. (Switch over to the Broadcom again, shut down, Uninstall the Intel, Install the other Intel, reboot. Set up the new Intel make sure it has latest firmware and driver, switch over to it, disable the Broadcom - kind of opportunity).
Also, I have taken another approach.
Someone suggested that it was a firewall issue that the firewall was "freezing everything out" which would explain my being able to ping, but not even to the first switch - maybe?
So, I removed Symantec and reinstalled the Symantec Client in "Servers - Basic Protection" mode which bypasses Symantec's integration and control of the internal Windows Firewall.
It has only been a couple of days, but I am hoping that this approach helps.
In the meantime, I am looking for a time to change-out my NIC - just in case it doesn't.

It is kind of you to offer your assistance.
Thank you.
Seth SimmonsSr. Systems AdministratorCommented:
I've requested that this question be deleted for the following reason:

Not enough information to confirm an answer.
awed1Author Commented:
I had tried one Intel NIC because I had seen someone online say it could be the Broadcom NIC.  That didn't help. Then I wasn't going to try it again, but I ran out of options. Your suggestion prompted me to buy another NIC, one that was on the Dell compatibility list.  At first, it still gave me trouble. It was only after tweaking its settings (Disabled RSS/TOE), the problem finally went away. I am not sure anymore if I had tweaked the previous NIC's settings that way. Thanks again, B.
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