Exchange 2013 - Outlook Setup

Hi There,

I have an Exchange 2013 server running on Windows 2012. My problem is that when I am setting up the manual connection to Exchange and put in the server name, click check name, I get this error:

The servername is correct and I can ping it. The user name is also correct. I have also tried this from multiple machines running different OS's and versions of Outlook, I get the same error.

I can configure Outlook when it does it automatically. I can also use EWS clients such as Outlook 2011.

Would anyone have any ideas what maybe going wrong here?

Thanks

Dave