User unable to login

A user of our application is unable to login. They are seeing the following 403 forbidden error being returned from our Kinde custom domain

auth.inrange.io

auth.inrange.io

. In the Kinde dashboard the user's profile reports Total sign-ins: 0 and Failed sign-ins: 0. Can you help me to diagnose and fix this login issue?

User unable to login - Kinde