In c# web api authentication works fine when I run my server under Visual Studio IIS Express, but always returns 401 when run under a development IIS server. The connectivity is verified. Can successfully fetch a token from either the dev PC or the IIS server. There is a 3 hour time difference between the dev PC and IIS server. I have tried many many variations for IIS setup and configuration but never works. I am using a modified version of Okta,AspNet - modified to be proxy aware. Works fine from local PC through proxy.