I've completed a migration from Exchange 2007 to Exchange 2013. The new server run on a Windows 2008 R2 VM . The old one was dismissed. The server works fine but client connectivity on the internal LAN is very slow.
When I look at the Outlook connection status the connection status is HTTPS and not TCP/IP (as it should be).
This problem was not resolved by unchecking the option "on fast network, connect using HTTP first ...".
Obviously Outlook users and Exchange 2013 are on the same subnet and connected via gigabit lan.