An evil-Twin attack is a type of wireless network attack that involves setting up a rogue access point that mimics a legitimate one. It can trick users into connecting to the rogue access point instead of the real one, and then intercept or modify their traffic, steal their credentials, launch phishing pages, etc. It is the most likely cause of the issue that users are experiencing slow speeds, unable to connect to network drives, and required to enter their credentials on web pages when working in the section of the building that is closest to the parking lot, where an external access point could be placed nearby.