the client is behind a firewall, and for some reasons, it could not set the Default Gateway, so, the client using DO has to manually support sock5. but here how currently work:

domain = (Domain)RemotingServices.Connect(typeof(Domain), string.Format(ServerURL, ipAdress, port.ToString()));

how to support sock5, I could not find any property to set the proxy settings.

I found System.Runtime.Remoting.Services.RemotingClientProxy, but only a little documents on it.