How to use AutoMapper

http://docs.automapper.org/en/stable/Getting-started.html

IMappingExpression<TSource, TDestination> CreateMap<TSource, TDestination>(MemberList memberList);

Mapper.Initialize(cfg => cfg.CreateMap<Order, OrderDto>());
//or
var config = new MapperConfiguration(cfg => cfg.CreateMap<Order, OrderDto>());

   IMappingExpression<TSource, TDestination> ForMember<TMember>(Expression<Func<TDestination, TMember>> destinationMember, Action<IMemberConfigurationExpression<TSource, TDestination, TMember>> memberOptions);

var mapper = config.CreateMapper();
// or
var mapper = new Mapper(config);
OrderDto dto = mapper.Map<OrderDto>(order);
// or
OrderDto dto = Mapper.Map<OrderDto>(order);

C# : Converting Base Class to Child Class

https://stackoverflow.com/a/25653977/3782855

'm surprised AutoMapper hasn't come up as an answer.

As is clear from all the previous answers, you cannot do the typecast. However, using AutoMapper, in a few lines of code you can have a new SkyfilterClient instantiated based on an existing NetworkClient.

In essence, you would put the following where you are currently doing your typecasting:

using AutoMapper;
...
// somewhere, your network client was declared
var existingNetworkClient = new NetworkClient();
...
// now we want to type-cast, but we can't, so we instantiate using AutoMapper
AutoMapper.Mapper.CreateMap<NetworkClient, SkyfilterClient>();
var skyfilterObject = AutoMapper.Mapper.Map<SkyfilterClient>(existingNetworkClient);

Here's a full-blown example:

 public class Vehicle
  {
    public int NumWheels { get; set; }
    public bool HasMotor { get; set; }
  }

  public class Car: Vehicle
  {
    public string Color { get; set; }
    public string SteeringColumnStyle { get; set; }
  }

  public class CarMaker
  {
    // I am given vehicles that I want to turn into cars...
    public List<Car> Convert(List<Vehicle> vehicles)
    {
      var cars = new List<Car>();
      AutoMapper.Mapper.CreateMap<Vehicle, Car>(); // Declare that we want some automagic to happen
      foreach (var vehicle in vehicles)
      {
        var car = AutoMapper.Mapper.Map<Car>(vehicle);
        // At this point, the car-specific properties (Color and SteeringColumnStyle) are null, because there are no properties in the Vehicle object to map from.
        // However, car's NumWheels and HasMotor properties which exist due to inheritance, are populated by AutoMapper.
        cars.Add(car);
      }
      return cars;
    }
  }