Here's my setup:
Mixed environment transitioning:
Exchange 2010 running on Server 2008 in a VM
Exchange 2013 running on Server 2012 in a VM
I have split dns so that autodiscover.domain.com points to my 2013 server internally and my 2010 server externally. When setting up new profiles in outlook internally, autodiscover seems to work fine. However, when I try moving the public autodiscover.domain.com DNS record over to the 2013, pretty much nothing works.
I know that the 2013 server is reachable from the outside because mail.domain.com will to go owa and ecp without a problem. I can log in to both without an issue.
If I point public DNS back to my 2010 server, then all is well again with outlook anywhere and mobile connectivity.
I'm not really sure what needs to be tweaked for the 2013 server to be ready to take over the day to day...