SBS 2011

I manage an SBS 2011 Server that started acting up a few days ago.

Internet is not accessible most times. After a FlushDNS, a few sites work for a little while.

Emails work to some domains. No particular pattern.

RDP, RWA and OWA can be accessed.

Ran Connect to Internet, Set up your Internet Address and Fix my Network wizards a few times.

DNS has two forwarders. Tried to update root hints but none of the servers resolve.

Tried using different DNS servers as forwarders.

Ran

Swapped modem/router, switch, replaced network cables.

Getting desperate now.
EitNTAsked:
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Larry Struckmeyer MVPConnect With a Mentor Commented:
Hi:
You did not mention the SBS BPA... download, install, run that and fix anything it finds.
www.sbsbpa.com

Verify that the only DNS server listed for any nic in the LAN is that of the SBS IP.

Do not disable IPV6

Give us the event ID and source of any error in the event logs that relates to your issue.

When the internet is not available, can you ping the LAN IP address of the router/firewall, the Wan IP and the IP of the ISP DNS servers?  Can you ping any known public web site such as yahoo.com?
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EitNTAuthor Commented:
Checked on http://www.yougetsignal.com/tools/open-ports/ that says ports 443 and 25 are not open.

Have checked the modem and confirm ports 443 and 25 are forwarded to the IP address of the server.

When doing an nslookup it times out. Default Server: Unknown. IP Address V6 not V4.
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smckeown777Connect With a Mentor Commented:
Which forwarders are you using? If ISP's remove them(or just add these)

208.67.222.222
208.67.220.220

Those are OpenDNS's dns server ip's

Can you show us output of

ipconfig /all

from your server...

1) Is this a new box? If not how long is it experiencing these issues?
2) What AV product is installed?
3) Windows patched to latest level?
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EitNTAuthor Commented:
Gentlemen

Thank you for your responses. I had tried all you suggested before posting.

When this problem occurred, we logged a job with the ISP who said it was not their problem.

This morning, after replacing the NIC in the server, in the unlikely event that this was the cause of the problem, I connected a laptop to the Modem and using the LAN IP address of the server as the DNS server, tried to ping/resolve internet sites like Google, BING etc.

When this failed, I called the ISP and read them the riot act. It took them less than 10 minutes to work out the external IP address of the modem was being routed through Sydney and not Adelaide as it should be. As soon as the routing was fixed everything worked fine.

Unfortunately, in less than two hours, the problem appeared again which makes me believe that this is being caused by a glitch in the ISPs system.

A job was logged at 10:45 am our time and we are still waiting for a response from the ISP.

Thank you both again for your input.
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