3.SPD cannot open site, in the log :Error when open web service: System.InvalidOperationException: A binding instance has already been associated to listen URI

Solution:

  I found the problem to be in the name used by the server and in the bindings in IIS.

In this installation I’m using a split DNS (eg the internal IP domain is equal to the external IP domain). The FQDN of the server is sp13.sp.com . The Windows name is sp13 and the Windows IP domain is sp.com.  I defined https://sp13.sp.com as the main URL of the server and http://sp13.sp.com and http://sp13 as alternate URLs. In the correspondent IIS web site I defined these bindings: 

ip address        protocol        virtual server        port

*        http                 80

*        http        sp13.sp.com        80

*        http        sp13        80

There was a conflict between the first (generic) binding and the third binding. The (WCF) client services (and other services, too) try to bind the same endpoint two times. 

I solved the problem deleting the first binding.

SharePoint Designer cannot open site error " the server could not complete your request"