Look in the web server config and make sure the local interface that is chosen in the dropdown is the one you are trying to log in from.
No change. There is only one interface on my Windows Server 2012 that runs BI. UI3 is still prompted for authentication. For reference, I am running UI3 version 113 and BI version 5.3.0.3. I have attached a couple of screenshots for reference. Any ideas, please let me know.