'base.Channel' threw an exception of type 'System.ServiceModel.CommunicationObjectFaultedException'

Something is sick with a .wsdl/SOAP web service, causing this error. MTOM is Message Transmission Optimization Mechanism. It sends binary data. In SOAP/XML, WS-* or WS-star will include WS-Policy, WS-Addressing, WS-Trust, WS-SecureConversation, WS-Transaction, etc. WS for web services, get it? Duplex channels describe the use of two frequency channels. A talks to B while B talks back to A on a seperate channel. The following in ConfigureServices in Startup.cs will allow IIS to always send credentials with web requests.

services.Configure<IISServerOptions>(options =>
{
   options.AutomaticAuthentication = false;
});

 
 

For Kestrel:

services.AddAuthentication(NegotiateDefaults.AuthenticationScheme).AddNegotiate();