title: Google Drive API OAuth 2.0: ERR_CONNECTION_REFUSED
body: <p>I enabled the Google Drive API in my personal GCP, set up my OAuth2 consent screen, and downloaded my credentials.json file. I'm now running this code from the <a href="https://developers.google.com/drive/api/v3/quickstart/python" rel="nofollow noreferrer">Python quickstart</a> in Colab:</p>
  
  <pre><code>from __future__ import print_function
  import pickle
  import os.path
  from googleapiclient.discovery import build
  from google_auth_oauthlib.flow import InstalledAppFlow
  from google.auth.transport.requests import Request
  
  # If modifying these scopes, delete the file token.pickle.
  SCOPES = ['https://www.googleapis.com/auth/drive.metadata.readonly']
  
  def main():
      """Shows basic usage of the Drive v3 API.
      Prints the names and ids of the first 10 files the user has access to.
      """
      creds = None
      # The file token.pickle stores the user's access and refresh tokens, and is
      # created automatically when the authorization flow completes for the first
      # time.
      if os.path.exists('token.pickle'):
          with open('token.pickle', 'rb') as token:
              creds = pickle.load(token)
      # If there are no (valid) credentials available, let the user log in.
      if not creds or not creds.valid:
          if creds and creds.expired and creds.refresh_token:
              creds.refresh(Request())
          else:
              flow = InstalledAppFlow.from_client_secrets_file(
                  'credentials.json', SCOPES)
              creds = flow.run_local_server(port=0)
          # Save the credentials for the next run
          with open('token.pickle', 'wb') as token:
              pickle.dump(creds, token)
  
      service = build('drive', 'v3', credentials=creds)
  
      # Call the Drive v3 API
      results = service.files().list(
          pageSize=10, fields="nextPageToken, files(id, name)").execute()
      items = results.get('files', [])
  
      if not items:
          print('No files found.')
      else:
          print('Files:')
          for item in items:
              print(u'{0} ({1})'.format(item['name'], item['id']))
  
  if __name__ == '__main__':
      main()
  </code></pre>
  
  <p>When I execute the code, I am prompted to login via Google's OAuth sign-in page, to give my program access to my Google account. I click Allow, then immediately see this page:
  <a href="https://i.stack.imgur.com/Clylw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Clylw.png" alt="Error screen"></a></p>
  
  <p>I've redone this without a VPN or firewall with no luck, and I don't know if this is a problem with my OAuth or creds setup in the Project. Thoughts?</p>