title: Why do I get 'System.UriFormatException: Invalid URI: Invalid port specified.' when using an IPv6 URI?
body: <p>Why does this <code>var uri = new Uri("ftp://1111:2222:3333::43/testing/1kb.zip");</code></p>
  
  <p>Throw this exception?</p>
  
  <blockquote>
    <p>System.UriFormatException: Invalid URI: Invalid port specified. at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind)</p>
  </blockquote>