title: asp.net core 2.1 preview 2 - signalR CORS issues and 405 on OPTIONS request
body: <p>Using the latest versions of signalR and @aspnet/signalr I still get issues connecting. I'm fairly sure the versions are exactly the same.<br>
  I've been following the <a href="https://blogs.msdn.microsoft.com/webdev/2018/02/27/asp-net-core-2-1-0-preview1-getting-started-with-signalr/" rel="nofollow noreferrer">startup project here</a>. But instead I'm using an Angular 5 application. I get issues with CORS headers and more specifically the OPTIONS request returns a 405 method not allowed.</p>
  
  <p><a href="https://i.stack.imgur.com/ojdeg.png" rel="nofollow noreferrer">Visual studio version here</a>.  </p>
  
  <p><a href="https://i.stack.imgur.com/4NoLE.png" rel="nofollow noreferrer">Typescript/javascript client version here</a></p>