NC 29/30 + OO ONLYOFFICE cannot be reached. Please contact admin

I also specified a great value for the leeway setting (for the clock difference between the OO server and the Cloud server):
In my config.php:

  'onlyoffice' => 
  array (
    'DocumentServerUrl' => 'https://oo.blah.com/',
    'verify_peer_off' => true,
    'jwt_secret' => '**********',
    'jwt_header' => 'Authorization',
    'jwt_leeway' => 2500,
  ),

Edit: updated successfully to NC 30.0.0 RC4