We just installed a 2013 CAS/Mailbox server in our Exchange 2007 environment and are running in coexistence while we migrate users over. So far I have only moved one 2007 mailbox over, a new account used for testing. Everything is working fine, OWA, ECP, ActiveSync, etc... When connecting Outlook to a 2007 mailbox autodiscover takes a couple seconds and Outlook opens fine. The problem is when connecting Outlook to a mailbox on the 2013 server. Autodiscover takes about a minute before it finally finds the settings and the mailbox takes about 30 seconds to open everytime. It generally times out, I click retry and the mailbox opens. Once in everything is good but the initial loading always takes a long time, double the time when opening Outlook with a shared mailbox attached. All autodiscover is autodiscover.domain.com, Exchange 2007 is all legacymail.domain.com aside from the components that need to point to 2013. We do not have any certificate issues, well that's not true, at some time in the last couple years someone applied a 3rd party cert to our domain.com root but not sure if that would cause this issue. Also, these are internal clients we are trying to get going with the 2013 mailbox, not external. I just applied a registry change that helped someone else out there by disabling IPv6 for all components but that did not work for us MS KB929852. Any suggestions? Right now I am thinking of changing the internalURI for autodiscover to the FQDN of the server but wanted to see if anyone had any ideas.
Jeremy