As Herwin's suggestion, I modified my regular expression and it worked. WP8.1 clients can now be successfully authorized. Thanks for you guys' help. Of course, adding unlang in authorization part is not good method as the accounting part don't use the same username that authorization part uses. Maybe through the operation of ntdomain is better. And I don't want proxying while only deploying a local host. I'm newcomer in FR and don't know how to do it.