WCF客户端响应使用ServiceModel Channel始终为NULL

Question

我正在使用.NET Core 2.1与我们拥有的旧版SOAP Web服务集成。

C＃代码

"No route found for "CONNECT /www.baidu.com:443""

从服务器返回的XML（通过Fiddler捕获）

[DataContract(Name = "registerResponse", Namespace = "urn:svcnet")]
public class RegisterResponse
{
    [DataMember(Name = "sessionKey")]
    public string SessionKey { get; set; }
}

[ServiceContract(Name = "svcnet", Namespace = "urn:svcnet")]
public interface IRegister
{
    [OperationContract(Name = "register")]
    RegisterResponse Register(string param1);
}

public class MyContext
{
    public void Register()
    {
        var serviceUrl = "https://myserviceurl";

        var endpoint = new EndpointAddress(new Uri(serviceUrl));

        var factory = new ChannelFactory<IRegister>(binding, endpoint);

        IRegister channel = factory.CreateChannel();

        var result = channel.Register("somevalue"); // <<< result is always null
    }
}

结果始终为null。在Google和Stack Overflow上花费了多个小时后，我使自己确信它静默地未能构造响应对象。有什么线索可以调试它，还是我的代码明显有问题？

我也尝试了以下方法，但结果相同（总是为空）

<?xml version="1.0" encoding="utf-16"?>
<SOAP-ENV:Envelope
    xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
    xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:svc="urn:svcnet">
  <s:Header xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" />
  <SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
    <svc:registerResponse>
      <sessionKey>ABC123</sessionKey>
    </svc:registerResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>