Recently was confronted with my lack of understanding using the auth_providers again, because I needed to authorize my daughters while being outside the local network, or not using a network at all.
Had setup Trusted networks (which worked for one of them signing in while being at the other side of the world…) but not for the others…
Then I realized they were not on a trusted network, and because of that got the error returning their computer wasn’t authorized.
I then, as admin, changed their password in the configuration settings, and they were able to login with user id and pw. Still that seems a bit of a hassle.
If this is the only way, I’d be able to live with that 
If this should/could be handled more elegantly I certainly would love some suggestions on how to.
Also, how could it be my daughter managed to login via Trusted networks, while not on the network…? Is this a one time setting (successful login while on the network), after which it simply authorizes anywhere?
Thanks for having a look