title: Microsoft.AspNet.SignalR.Client Start error. Could not create SSL/TLS secure channel
body: <p>I am using SignalR from Microsoft.AspNet.SignalR.Client in a client WPF C# application. The SignalR host is a ASP.NET MVC web app where the SignalR Hub is created from Microsoft.AspNet.SignalR. Both projects are using .NET4.5.2</p>
  <p>I use a port mapping tool called <strong>ngrok</strong> from <strong>ngrok.com</strong> to create external URLs that point to my local Visual Studio 2019 development environment.</p>
  <p>I have 2 accounts with ngrok. One for my personal testing and another for a client. Both URLs point to my development environment with the exact same config with the exception of the AuthToken/LicenseKey. The problem I am facing is that when the WPF client is using my personal <strong>ngrok</strong> account to start a connection to SignalR, all is perfect. But when I change the URL to use the clients <strong>ngrok</strong> account, SignalR fails to start the connection with the following error...</p>
  <blockquote>
  <p>System.Net.Http.HttpRequestException: An error occurred while sending
  the request. ---&gt; System.Net.WebException: The request was aborted:
  Could not create SSL/TLS secure channel.    at
  System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult)<br />
  at System.Net.Http.HttpClientHandler.GetResponseCallback(IAsyncResult
  ar)    --- End of inner exception stack trace ---</p>
  </blockquote>
  <p>I have searched the web and tried a number of suggestions (Not just specific to SignalR but the &quot;Could not create SSL/TLS secure channel&quot; error in general) and nothing has worked. I.e. in my hosts Startup.cs ...</p>
  <blockquote>
  <p>ServicePointManager.Expect100Continue = true;</p>
  </blockquote>
  <blockquote>
  <p>ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;</p>
  </blockquote>
  <blockquote>
  <p>ServicePointManager.ServerCertificateValidationCallback += (sender,
  cert, chain, sslPolicyErrors) =&gt; true;</p>
  </blockquote>
  <p>Both URLs use https and have a valid wildcard cert issued to <strong>ngrok</strong> by R3. The SignalR host is also a website. Using either URL, the website responds and serves up pages and the lock icon is visible in the URL address bar of the browser (I use Chrome).</p>
  <p>So I am at a loss as to why SignalR fails when I use my clients <strong>ngrok</strong> URL but works fine with my personal one. Can anyone help please? It would be very much appreciated.</p>