In preparation for Pokémon Ultra Sun and Ultra Moon, it has been announced that the Pokémon Global Link will be down for updating from November 10th, 2017 until November 17th, 2017. A special gift will be given out when the service returns on November 17th, 2017.

Pokémon Global Link Update Beginning November 10th, 2017

To prepare for the launch of the Pokémon Ultra Sun and Pokémon Ultra Moon video games, the Pokémon Global Link will be down from November 10 until November 17, 2017. During this time, players will not be able to access the site. This includes functionality such as the QR Code Rental feature.

When the site returns on November 17, be sure to register your new Pokémon Ultra Sun or Pokémon Ultra Moon game to receive a special gift!

Source: https://3ds.pokemon-gl.com/information/713eb1e5-67f0-4816-a0cf-893b05de8e0a