Ver 3.9 IIS Setup question

I have installed nopcommerce ver 3.9 as a site on iis 8.5 windows server 2012 r2.
If I use the default wildcard settings for port 80, I can browse the site and open nopcommerce.

I have more than 1 store and each has its own external IP address.
The router routes the external ip address to an internal ip address (one per store) that is set up on the webserver's network adapter.  DNS also has A records pointing the name to the same internal IP address.

If I remove the wildcard port 80 address in the bindings and replace it with one of the internal ip addresss that appear in the ip drop down, for port 80, and leave the host name blank, the nop website opens.

If I add the host name to the bindings, the site will not open saying the page cannot be displayed.

If I ping the hostname, it resolves to the internal ip address used in the bindings.

Any suggestions on why it won't open with the hostname in the binding?  A second question is how I open the website to the corresponding store based on the ip/hostname.

Thanks,
Rick

Problem solved.
The web was an upgrade and being tested.  At that point, the ssl certs had not been added to the web bindings, just a port 80 http binding.  However, in the database, the site configuration was set to enable ssl and this prevented loading of the site.  I was able to open a store not configured with ssl, go to admin settings and disable the ssl on the other store.  Once I did that, I could log in. I experienced the same issue in 3.9 and 4.0.