Android 5.0+( Starting from Lollipop ) have the default behavior of splash page closing after receiving 204 response in the end of the login. However in older Android phones before Lollipop the hotspot page stays up.
The behavior is controlled by Android OS. User doesn't seem to have easy way to control the behavior.
On the post-authentication rules or firewall, block the following URLs:
- clients4.google.com
- clients3.google.com
- clients2.google.com
- clients1.google.com
- android.clients.google.com
- connectivitycheck.android.com
- connectivitycheck.gstatic.com