I have a Windows 2008R2 domain with Exchange 2010. OWA was working but I would get the certificate error problem in the browser so I added a 3rd party certificate from Entrust for OWA access. After doing this, I can't access OWA at all. I get the error that Windows cannot display the page, with the following additional information.
This problem can be caused by a variety of issues, including:
Internet connectivity has been lost.
The website is temporarily unavailable.
The Domain Name Server (DNS) is not reachable.
The Domain Name Server (DNS) does not have a listing for the website's domain.
If this is an HTTPS (secure) address, click Tools, click Internet Options, click Advanced, and check to be sure the SSL and TLS protocols are enabled under the security section.
I get the same error inside the LAN and from the Internet.
I also can't access Exchange from the EMC or EMS now. However, the exchange server is running and I can send and receive email.
The external URL is https://mail.gssec.k12.in.us/owa