iOS Sample Code
--------------------------------------------
HubConnection _conn; IHubProxy _hub; bool _started; 
 const string SERVER_URL = "https://<DomainName>.com:8085/signalr";
 public async Task StartAsync(string deviceId)
 {
     try
     {
         if (IsConnected) return;

         _deviceId = deviceId;

         _conn = new HubConnection(SERVER_URL);
         _hub = _conn.CreateHubProxy("SFKRemoteHub");

         _hub.On<string, string, string>("Receive",
         async (from, type, json) =>
         {   OnReceive?.Invoke(from, type, json);
         });

         _conn.Reconnected += async () =>
         {
             if (_conn.State != ConnectionState.Connected)
             {
                 return;
             }

             await _sendLock.WaitAsync();

             try
             {
                 await _hub.Invoke("Register", _deviceId);
             }
             finally
             {
                 _sendLock.Release();
             }
         };

         _conn.Closed += () => _started = false;

         await _conn.Start(); 
         await _hub.Invoke("Register", _deviceId);

         _started = true;
     }
     catch (Exception ex)
     {
     }
 }
  await _conn.Start();  Error ouucre here
  
  
Server Side Sample Code
--------------------------------------------

using Microsoft.AspNet.SignalR;
using Owin;
using System.Threading.Tasks;

[assembly: Microsoft.Owin.OwinStartup(typeof(API.Startup))]

namespace ComrogenAPI
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            app.MapSignalR("/signalr", new HubConfiguration());
        }
    }

    public class SFKRemoteHub : Hub
    {
        public async Task Register(string deviceId)
        {
            await Groups.Add(Context.ConnectionId, deviceId);
        }
        public async Task Relay(string fromDevice, string toDevice, string messageType, string json)
        {
            await Clients.Group(toDevice).Receive(fromDevice, messageType, json);
        }
    }
}