How to disable IPv6 on Android 6

Hi,

i'm trying to find the way to disable IPv6 on Android device TC75X Marshmallow (6.0.1).

I've collected info on Internet and this is quite easy with current Android version (8), just selecting IPv4 option from Network/APN menu.

but it looks like this menu is not available in Android 6.

any tips?

thanks!

Matteo