iOS (and presumably Android) has a similar functionality, but at least in iOS's case it's to find out if the device should consider this wifi to be 'working' (a

iOS (and presumably Android) has a similar functionality, but at least in iOS's case it's to find out if the device should consider this wifi to be 'working' (and send traffic via WiFi) or 'blocked' (and continue using the mobile data network). I can't think of any reason to have this failover behaviour on a consumer router that isn't multihomed. It's not the router's job to ensure that my internet is working according to some predefined rules, when there is no tangible benefit to doing so.