When AO3 experiences technical issues:
You're referring to the AO3 (Archive of Our Own) mirror feature! ao3 mirror
Mirror sites often use Content Delivery Network (CDN) optimization and localized servers to improve access speeds dramatically. For users in certain geographic regions, a mirror hosted nearby can load pages in under two seconds, compared to ten seconds or more for the main site located halfway across the world. When AO3 experiences technical issues: You're referring to
During periods of intense traffic, heavy DDoS attacks, or scheduled maintenance, official servers can temporarily go offline. Mirrors distribute the traffic load across independent infrastructure. Official vs. Unofficial Mirrors: The Security Risk heavy DDoS attacks
If you regularly experience AO3 access problems: