Enlarge / Cloudflare's DNS service uses the 1.1.1.1 address. (credit: Cloudflare) AT&T has been blocking the new Cloudflare DNS service, but AT&T says the blocking was unintentional and that it will fix the problem soon. The blocking is affecting AT&T home Internet customers who use an AT&T gateway. Cloudflare unveiled its DNS service on April 1, and users in DSLReports forum threads almost immediately started complaining that they couldn't access it.