I have two Exchange 2013 servers with CAS and Mailbox and two Exchange 2010 servers with Hub, CAS and Mailbox. The 2010 servers operate perfectly. The two Exchange 2013 servers have been added to the environment and setup as a IPless DAG. I have some strange behaviours with ECP and OWA websites:

* Server 1: ECP works fine using local FQDN or Loadbalanced FQDN, OWA gives ":-( something went wrong Sorry we can't get that information right now...", sometime I get a blank page but don't know what the difference is. User accounts on the 2013 servers work for OWA but once I have logged in on a computer with a 2013 account and then try to use a 2010 account it keeps trying 2013 OWA.

* Server 2: ECP works fine using local FQDN or Loadbalanced FQDN, OWA works with local or Loadbalaced FQDN and happily redirects to the 2010 servers as required. If I connect to this server and try and login to a 2013 account via OWA it redirects to 2010 and tells me to connect to Server 1.

Both Exchange 2013 are running SP1CU9. I have tried re-setting the Virtual Directories on Server 1 as well as some changes to binding in IIS but nothing seems to make any difference. The Exchange servers are in different DataCentres but otherwise are identical.

Any clues would be good.

Hi,

What's your OWA configuration in your environment? Are you using different AD sites? Please run the following command to have a check:

Get-OWAVirtualDirectory | FL Identity,*Auth*,*URL*

Please refer to the following article to know more about the proxy and redirection connection in an Exchange 2013 Coexistence Environment:

http://blogs.technet.com/b/exchange/archive/2014/03/12/client-connectivity-in-an-exchange-2013-coexistence-environment.aspx

Regards,

After much fighting with this the fix was to make sure that Windows Integrated Login was enabled on Exchange 2010 and the missing point in most posts was to make sure you actually selected providers for Windows Integrated Login, this would generally be Auto Negotiate but adding all of them didn't seem to cause any harm.

• Marked as answer by Neal Blount 9 hours 27 minutes ago