I use Free WiFi Spot to automatically connect to WiFi hotspots that use login/password authentication. This application also checks internet connectivity. When AdBlock Plus is active, Free WiFi Spot keeps saying that connectivity is broken and presents me with a form to enter a login/passord as if I were talking to a hotspot portal. If I turn it off, all works well.
Free WiFi Spot is at : https://play.google.com/store/apps/deta ... eewifispot if you want to try and identify what is wrong.