asp.net core 添加soap web service System.ServiceModel.CommunicationObjectFaultedException

如何解决asp.net core 添加soap web service System.ServiceModel.CommunicationObjectFaultedException

我想使用soap网络服务。我收到这个错误

System.ServiceModel.CommunicationObjectFaultedException: 'The 通信对象，System.ServiceModel.ChannelFactory`1[.....]， 无法用于通信，因为它处于故障状态。'

我的代码是这样的：

    public Service_res getUnits()
    {
        myServiceClient client = new myServiceClient("SoapHttpBinding");

        client.ClientCredentials.Windows.ClientCredential.UserName = "usrname";
        client.ClientCredentials.Windows.ClientCredential.Password = "pass";

        Service_res res = client.myServiceFunc(new Service_req());
        return res;
    }