I can't use Wi-Fi on my Samsung Galaxy S8 Android 7.0
Cause 4 of 4: The phone is connected to a Wi-Fi network, but you're not logged on
Some Wi-Fi networks require you to log on via a web page.
Solution: Open the internet browser on your phone and try to load a web page. The internet browser is redirected to the homepage of the Wi-Fi network. Follow the instructions on the screen to log on to the Wi-Fi network.
