DHCP option 43 is often used to indicate if a mobile network is metered. (May be other ways, this is the one I'm most familiar with.) I'm guessing your "spare mobile phone" is Android?
Apple caches a lot of info about networks it connects to. So it's probably caching that it received this option and "knows" that network to be metered.
Best solution for this is to have either more control over your mobile network so it's not sending that option, or more easily, name the mobile network something else from your home one.
Apple caches a lot of info about networks it connects to. So it's probably caching that it received this option and "knows" that network to be metered.
Best solution for this is to have either more control over your mobile network so it's not sending that option, or more easily, name the mobile network something else from your home one.