This tutorial shows how you can disable IPv6 on Android when using mobile network.
Please bear in mind, the steps may slightly vary depending on the version of Android you're running.
- Open the Settings menu of your Android phone.
- Head into SIM cards & mobile networks section.
- Click on one of the two SIM cards that you're currently using. This will open the SIM card settings menu.
- Find Access Point Names and click on it.
- Next to the network you're using, press on the right-pointing arrow.
- Scroll down to APN protocol and APN roaming protocol, and change both of their settings to IPv4.
That's it. You've successfully turned off IPv6.