I've got 2 sim cards from the same mobile network provider with the same "unlimited" data plan.
Card number one works great when tethering from an android phone. And also from a 4G router (mifi) device.
Card number two sometimes works with that very same android phone. But get's blocked when I use a 4G router (get redirected to a web page stating that I'm up to no good). Sometimes, when tethering from an android phone, I get very slow speeds (<1Mbps down) but very fast speeds from the phone itself.
I know that it is possible to know when someone is tethering (something to do with TTL) but how exactly do they do it?
And why does it work for sim card number one but not for sim card number two with the same data plan?