How Does Android Know a Wi-Fi Network Is Fast or Slow Before I Connect?

Google recently introduced a new feature into Android 8.1 Oreo that displays how good a public Wi-Fi network is before you connect to it. Using just simple terms like Slow, OK, Fast, and Very Fast, it will let you quickly gauge whether a network is worth connecting to, or if you’re better off just sticking with mobile data.
by Cameron Summerson via How-To Geek