Server keeps losing internet connectivity

I just built a new Windows 2012 R2 server on an older Dell PowerEdge 1900.  The server built very easily and the server is running very well.  It is a pretty clean install, with nothing major installed other than AD and IIS.  After it was built I installed a third party proxy server (safesquid).  After it was configured everything seemed to be working well until suddenly no one could access the internet.  I disabled the proxy on my workstation and I was able to access the internet.  So I called Safesquid and after some troubleshooting, we found that it was the server.  If I disabled the proxy the server could not access the internet.  Since the server could not access the net, when the proxy was running, neither could the workstations.

So I reboot the server, and then everything was find again.  A day later, same problem.  I tried to reset winsock, but that just asked for a reboot which I know would solve the problem.  I have rebooted the server three times in the past three days and each time it solves the problem.  When the server looses the internet connectivity, it still has local network connectivity.  I can access files from the server and from the server I can access my workstation.  I checked DNS, and it is set up correctly.

Does anyone have any thought about how to troubleshoot this?

Phil Goldwasser
pgoldwasserAsked:
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arnoldCommented:
Look at the event logs dealing with network interfaces.
Check firewall if any to make sure it is not blocking the server for exceeding traffic/session initiation thresholds.
Exempting the server/'s IP from those thresholds should resolve the lockout.
pgoldwasserAuthor Commented:
Thanks for responding.  I forgot to add that I have turned off the Windows firewall on the server.  I will take a look at the event log.  The system log I would assume, yes?
Wayne88Commented:
Have you done a traceroute from a workstation to say www.yahoo.ca and see the trace stop at your proxy server IP address?

https://support.microsoft.com/en-us/kb/162326
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pgoldwasserAuthor Commented:
I have not.  The next time this happens I will do that, however, if I turn off the proxy on my workstation when this happens, I can then browse the internet.  So it seems pretty clear that the problem is at the server.  If I then turn the proxy off at the serer itself, I can still browse from my worksation, but I CANNOT browse from the server.  So it seems that every day or so, the server looses connectivity to the internet.
Wayne88Commented:
Also, can you ensure that your server is running the latest NIC drivers.
arnoldCommented:
Yes, not the windows firewall, the external firewall if any.  Windows firewall will not be so discremenant as to allow shared access while denying itself external access.
pgoldwasserAuthor Commented:
The next time this happens, I will turn off my firewall for a moment and see if the server can browse.  The firewall is very basic and all traffic is allowed out.
arnoldCommented:
I would strongly advise against turning off your external firewall.

See whether it has any events indicating it is locking out the server.

What is the make/model of the firewall?
Is it configurable?
pgoldwasserAuthor Commented:
The firewall is a basic on that is on the FiOS router, so there is very little I can configure there.
arnoldCommented:
Ok, let me ask you the following, your DNS server configuration is local on the win2k12?
Did you configure forwarders such that any and all requests outside your AD domain are sent/transmitted to your ISPs DNS servers? Disable the forwarders allowing your DNS server using the ROOT hints to get the answers itself. And see if that resolves the issue.
Check whether the server is or is not exempt from relying on the proxy running on it.

Try using ping/tracert as pointed out earlier, make sure you have IPs 8.8.8.8

What DNS servers do the workstations rely on? Do they only have the 2012 server, or they have the iisps?


Given workstations can access the server means the network is fine and will not be/reflect events unless another IP matching the server is brought up by another system creating an IPmconflict.

The system might be accessed via IPv4 or IPv6 by workstations.
Ping server from workstation and see which ........... Ip responds
pgoldwasserAuthor Commented:
DNS is on the local W2k12 server.  Forwarders are set to use 8.8.8.8 and 4.2.2.1.

The server itself can relay as far as I know.  Something interesting I noted is that the proxy server uses address 127.0.0.1 the local address, while the server is actually 192.168.2.5.  

Are you suggesting that when the problem occurs, I take off the forwarders to 8.8.8.8 and 4.2.2.1?  i can certainly try that and see what happens.  Workstations have just server for DNS.

IPv6 is disabled on the server and workstations.
arnoldCommented:
If the proxy uses localhost/127.0.0.1 that means the clients can never send requests to it. So it never works, not intermittently as I think your question suggests.

Look at the config for listen bind even 127.0.0.1 and change the entry to 0.0.0.0
And see if that change after restarting the proxy service resolves the issue.

It has to be listening on all interfaces 0.0.0.0:proxyport
I would advise against configuring forwarders.  Using forwarders, your server keeps sending the same requests back out versus caching a response it received for the set time of the record.
netstat -an | find ":proxyport"
pgoldwasserAuthor Commented:
I uninstalled the proxy server and then everything went back to normal.

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arnoldCommented:
The issue is a misconfiguration on the proxy server/binding it to a localhost which is only accessible on the server where it runs.
pgoldwasserAuthor Commented:
I uninstalled the offending software and everything was fine after that.
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Windows Server 2012

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