C# Asp.Net Mvc Impesonate in inner Ajax

Scenario - an MVC app, while in the C# we are calling a REST api. To make the job easier we are using RestSharp The API is an inner api, using windows authentication my steps: 1. using NtlmAuthenticator 2. using default credentials 3. web config - added all the following 4. IIS -> your site -> Authentication -> changed to the following