Windows authentication process can take place on the user-mode (IIS worker process) or kernel-mode (HTTP.SYS). For the kernel-mode, there is a limitation: You can add maximum 64 bindings to your site. If you add 65 or more bindings, IIS displays “401.2 Unauthorized: Logon Failed Due to Server
Configuration with No Authentication” error even though the credentials are correct.
A change for Windows Server 2008 R2 or Windows Server 2012 R2 is not expected for this limitation.
Use user-mode authentication for your application to get around binding limitation of kernel-mode.
Steps to use user-mode authentication instead of kernel-mode: