RestSharp with JWT-authentication doesn't work

Question

This is the page where I "learned" how to do it: https://stormpath.com/blog/token-authentication-asp-net-core

But for me this is not working (doesn't work with Fiddler, too) There is this controller for my ApplicationUser-model:

[Authorize] //works when it's not set, doesn't work when it's set
[Route("api/[controller]")]
public class ApplicationUserController : Controller
{
    private IRepository<ApplicationUser> _applicationUserRepository;

    public ApplicationUserController(IRepository<ApplicationUser> applicationUserRepository)
    {
        _applicationUserRepository = applicationUserRepository;
    }

    [HttpGet("{id}")]
    public ApplicationUser Get(int id)
    {
        return _applicationUserRepository.Get(id);
    }
}

and there's my wrapper for RestSharp to get all applicationusers:

public Task<T> GetResponseContentAsync<T>(string resource, int id) where T : new()
{
    RestRequest request = new RestRequest($"{resource}/{{id}}", Method.GET);
    request.AddUrlSegment("id", id);
    if (!AuthenticationToken.IsNullOrEmpty(true))
    {
        request.AddHeader("Authorization", string.Format("Bearer {0}", AuthenticationToken));
        _client.Authenticator = new JwtAuthenticator(AuthenticationToken);
        _client.Authenticator.Authenticate(_client, request);
    }

    TaskCompletionSource<T> tcs = new TaskCompletionSource<T>();
    _client.ExecuteAsync<T>(request, response =>
    {
        tcs.SetResult(response.Data);
    });
    return tcs.Task;
}

From my web-client application I want to login with JWT (Token-Authentication) what works. After login I get e.g. this access_token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJURVNUIiwianRpIjoiZTBjYjE0NjgtYzBmOS00ZTM4LTg4ZjgtMGM4ZjNmYjMyNjZmIiwiaWF0IjoxNDcwOTUwMTA0LCJuYmYiOjE0NzA5NTAxMDQsImV4cCI6MTQ3MDk1MDQwNCwiaXNzIjoiRXhhbXBsZUlzc3VlciIsImF1ZCI6IkV4YW1wbGVBdWRpZW5jZSJ9.a9_JK2SG3vzc6NSOB0mZXqHlM9UAEXUHHrrijAQUsX0

without the Authorize-attribute I get the ApplicationUser, but when setting the Attribute, the result is null (since the web-api is not getting called)

the wrapper-call looks like this:

//this works, token-value is set
string token = new RepositoryCall("http://localhost:54008/").Login("token", "TEST", "TEST123");

string accessToken = JsonConvert.DeserializeObject<Dictionary<string, string>>(token)["access_token"];
ViewData["Result"] = accessToken;

ApplicationUser userAfterLogin = await new RepositoryCall("http://localhost:54008/api") 
    { AuthenticationToken = accessToken }
    .GetResponseContentAsync<ApplicationUser>("ApplicationUser", 2);

and here userAfterLogin is null.

I'm trying to get the login since two weeks but I still don't get it right..

Any idea what I'm doing wrong? Maybe a wrong request-header-value for authorization?

Update

this is my Startup.Configure where I configured to use the Bearer / JWT:

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    loggerFactory.AddConsole(Configuration.GetSection("Logging"));
    loggerFactory.AddDebug();

    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
        app.UseDatabaseErrorPage();
        app.UseBrowserLink();
    }
    else
    {
        app.UseExceptionHandler("/Home/Error");
    }

    app.UseStaticFiles();

    app.UseIdentity();
    var secretKey = "mysupersecret_secretkey!123";
    var signingKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(secretKey));

    // Add external authentication middleware below. To configure them please see http://go.microsoft.com/fwlink/?LinkID=532715
    var options = new TokenProviderOptions
    {
        Audience = "ExampleAudience",
        Issuer = "ExampleIssuer",
        SigningCredentials = new SigningCredentials(signingKey, SecurityAlgorithms.HmacSha256),
    };


    var tokenValidationParameters = new TokenValidationParameters
    {
        // The signing key must match!
        ValidateIssuerSigningKey = true,
        IssuerSigningKey = signingKey,

        // Validate the JWT Issuer (iss) claim
        ValidateIssuer = true,
        ValidIssuer = "ExampleIssuer",

        // Validate the JWT Audience (aud) claim
        ValidateAudience = true,
        ValidAudience = "ExampleAudience",

        // Validate the token expiry
        ValidateLifetime = true,

        // If you want to allow a certain amount of clock drift, set that here:
        ClockSkew = TimeSpan.Zero
    };


    app.UseJwtBearerAuthentication(new JwtBearerOptions
    {
        AutomaticAuthenticate = true,
        AutomaticChallenge = true,
        TokenValidationParameters = tokenValidationParameters
    });

    app.UseCookieAuthentication(new CookieAuthenticationOptions
    {
        AutomaticAuthenticate = true,
        AutomaticChallenge = true,
        AuthenticationScheme = "Cookie",
        CookieName = "access_token",
        TicketDataFormat = new CustomJwtDataFormat(
            SecurityAlgorithms.HmacSha256,
            tokenValidationParameters)
    });

    app.UseMiddleware<TokenProviderMiddleware>(Options.Create(options));
    app.UseMvc(routes =>
    {
        routes.MapRoute(
            name: "default",
            template: "{controller=Home}/{action=Index}/{id?}");
    });
}

Answer 1

If you recive authorizacion error or using postman you realize that you are being asked to redirect to login just decorate your class with:

[Authorize(AuthenticationSchemes = "Bearer")]

By default .Net uses cookie based auth, with that annotation you swicht to token based one