Have connectivity check on on my device allowed.
Sometimes when attempting to load the captive portal from the notifications area (as it's shown here after few seconds upon connecting to WiFi), it just won't pop up the browser.
And instead the WiFi toggle in the drop down menu (Quick Settings Panel) is, also, after few seconds since the click on the captive portal notification, switched on disabled state.
So in this case, need to start WiFi manually again and not being able see captive portal.
What could be the cause? Except for connectivity check, what else is needed for this to work?