Website authentication page fails to open and displays an invalid IP address message

If your are trying to connect your device to a public wireless network, but the authentication page fails to load and displays a message saying that the IP address is invalid, it means the IP address of that network has changed.

Solution:

To solve this, on your device go to Settings > Wi-Fi and tap and hold on the name of the network that cannot access the Internet.

Select Modify network > Show advanced options > IP Settings and set the IP to Dynamic. Afterwards, open the browser, go to its settings and restore it to the default settings.