Unable to perform API Integration tests involving IdentityServer 4

[codefinity]

Oeuvre.API.IntegrationTests/IdentityAccess/RegistrationIntegrationTests.cs -- Get_GetAllRegistrants_Valid_Success

Able to get the token from the Identity Server, but when the token is sent to the server to service that requires Authentication, it throws the following error.

System.InvalidOperationException: IDX20803: Unable to obtain configuration from: 'http://localhost:5000/.well-known/openid-configuration'.
---> System.IO.IOException: IDX20804: Unable to retrieve document from: 'http://localhost:5000/.well-known/openid-configuration'.
---> System.Net.Http.HttpRequestException: No connection could be made because the target machine actively refused it.
---> System.Net.Sockets.SocketException (10061): No connection could be made because the target machine actively refused it.
at System.Net.Http.ConnectHelper.ConnectAsync(String host, Int32 port, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at System.Net.Http.ConnectHelper.ConnectAsync(String host, Int32 port, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.ConnectAsync(HttpRequestMessage request, Boolean allowHttp2, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.CreateHttp11ConnectionAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.GetHttpConnectionAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean doRequestAuth, CancellationToken cancellationToken)
at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Net.Http.DiagnosticsHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Net.Http.HttpClient.FinishSendAsyncBuffered(Task1 sendTask, HttpRequestMessage request, CancellationTokenSource cts, Boolean disposeCts) at Microsoft.IdentityModel.Protocols.HttpDocumentRetriever.GetDocumentAsync(String address, CancellationToken cancel) --- End of inner exception stack trace --- at Microsoft.IdentityModel.Protocols.HttpDocumentRetriever.GetDocumentAsync(String address, CancellationToken cancel) at Microsoft.IdentityModel.Protocols.OpenIdConnect.OpenIdConnectConfigurationRetriever.GetAsync(String address, IDocumentRetriever retriever, CancellationToken cancel) at Microsoft.IdentityModel.Protocols.ConfigurationManager1.GetConfigurationAsync(CancellationToken cancel)
--- End of inner exception stack trace ---
at Microsoft.IdentityModel.Protocols.ConfigurationManager`1.GetConfigurationAsync(CancellationToken cancel)
at Microsoft.AspNetCore.Authentication.JwtBearer.JwtBearerHandler.HandleAuthenticateAsync()
Exception thrown: 'System.InvalidOperationException' in System.Private.CoreLib.dll
Exception thrown: 'System.AggregateException' in System.Private.CoreLib.dll
An exception of type 'System.AggregateException' occurred in System.Private.CoreLib.dll but was not handled in user code
One or more errors occurred.