Laravel - Auth :: attempt

Good morning community of Laravel, today I come with a challenge, I hope your favorable answers.

I would like to be able to authenticate myself with users of two different databases. Validate information is not a problem. In my application I have the connections prepared. (config / database.php I have configured a connection for 'db1' and 'db2') My doubt really arises when I customize the login, I use the Auth :: attempt code, which uses the default connection even if I try to set the Connection of the User model:

$user = \App\User; 
$user->setConnection('mysql2');
if(Auth::attempt($credencials)){
   return Redirect::to('/home');
}

This gives me an error because I try to validate data from db2 (name of the connection: mysql2). Auth :: attempt is configured to use the default connection in this case 'mysql' (database db1).

In this case I want to achieve a custom login at this level. I appreciate your answers.