IEX API: Not a WebSocket handshake response.

Just installed WebSocketSharp and checking it out first time. I am trying to access the IEX API: https://iextrading.com/developer/docs/ using this simple code from the example:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using WebSocketSharp;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var ws = new WebSocket("wss://ws-api.iextrading.com/1.0"))
            {

                ws.OnMessage += (sender, e) =>
                    Console.WriteLine("Data: " + e.Data);

                ws.Connect();
                Console.ReadKey(true);
            }
        }
    }
}

However, I am getting: |Fatal|WebSocket.doHandshake|Not a WebSocket handshake response.

I've gotten it to run with Javascript, so I am not sure if there's a problem here with WebSocketSharp, or my method connecting to this API? Thanks!!

Start with the reported ConsoleApp2 example, the WebSocket constructor for wss://ws-api.iextrading.com/1.0, and the ws.Connect() call. Reproduce the handshake error and compare the request and response with the JavaScript client that reportedly works. Done means identifying whether the endpoint or WebSocketSharp produces the incompatible handshake and documenting a reproducible fix or limitation.