title: Angular Universal and Express JS connection rejected with Http failure response for unknown url Error in console
body: <p>I've been trying to get Angular Serverside Rendering to work, I have gotten to a point where the static portion works perfectly but for API calls, I get a HttpErrorResponse - Http failure response for unknown url error in console, which is the same error I get when the API server is closed. I haven't used any relative urls for API calls, its all absolute urls with https.</p>
  
  <pre><code>HttpErrorResponse {
    headers:
     HttpHeaders { normalizedNames: Map {}, lazyUpdate: null, headers: Map {} },
    status: 0,
    statusText: 'Unknown Error',
    url: null,
    ok: false,
    name: 'HttpErrorResponse',
    message: 'Http failure response for (unknown url): 0 Unknown Error',
    error:
     ProgressEvent {
       type: 'error',
       target:
        XMLHttpRequest {
          onloadstart: null,
          onprogress: null,
          onabort: null,
          onerror: null,
          onload: null,
          ontimeout: null,
          onloadend: null,
          _listeners: [Object],
          onreadystatechange: null,
          _anonymous: undefined,
          readyState: 4,
          response: null,
          responseText: '',
          responseType: 'text',
          responseURL: '',
          status: 0,
          statusText: '',
          timeout: 0,
          upload: [XMLHttpRequestUpload],
          _method: 'POST',
          _url: [Url],
          _sync: false,
          _headers: [Object],
          _loweredHeaders: [Object],
          _mimeOverride: null,
          _request: null,
          _response: null,
          _responseParts: null,
          _responseHeaders: null,
          _aborting: null,
          _error: null,
          _loadedBytes: 0,
          _totalBytes: 0,
          _lengthComputable: false },
       currentTarget:
        XMLHttpRequest {
          onloadstart: null,
          onprogress: null,
          onabort: null,
          onerror: null,
          onload: null,
          ontimeout: null,
          onloadend: null,
          _listeners: [Object],
          onreadystatechange: null,
          _anonymous: undefined,
          readyState: 4,
          response: null,
          responseText: '',
          responseType: 'text',
          responseURL: '',
          status: 0,
          statusText: '',
          timeout: 0,
          upload: [XMLHttpRequestUpload],
          _method: 'POST',
          _url: [Url],
          _sync: false,
          _headers: [Object],
          _loweredHeaders: [Object],
          _mimeOverride: null,
          _request: null,
          _response: null,
          _responseParts: null,
          _responseHeaders: null,
          _aborting: null,
          _error: null,
          _loadedBytes: 0,
          _totalBytes: 0,
          _lengthComputable: false },
       lengthComputable: false,
       loaded: 0,
       total: 0 } }
  </code></pre>