How does a device know if it has "Internet Access" or "No Internet"?
My laptop can connect to a local network, but it also somehow knows whether or not I can get 'past" that LAN to the wider Internet. If I can't, it usually means I haven't registered for access with the hotel or campus or whatever.
How does it know?
Is the device trying to connect to something "on the Internet," getting denied, and using that as a metric?