In this article, the author explains how to change the captive portal check URL on an Android phone. They start by defining what a captive portal is – a page that needs to be accepted before being able to access the internet on public or hotel WiFi networks. The author then highlights the potential privacy concern of the default captive portal URL, which contacts Google’s servers every time the user switches networks. To address this, the author suggests self-hosting the captive portal page using a web server and a PHP script. They provide instructions on how to change the URL on the phone and offer their own URL as an option.
https://www.encrypted.at/android-captive-portal/