The IPv6 Internet Protocol is integrated in many Linux distributions, but if it is not going to be used, it is convenient to disable it in order to avoid issues derived from inadequate configurations. In case of Linux, it can be disabled from the GRUB bootloader.
The first step will be to check that we have access as super user, to be able to edit the GRUB file with the text editor and make the changes mentioned below. When the file is opened, the lines GRUB_CMDLINE_LINUX_DEFAULT ="" and GRUB_CMDLINE_LINUX ="" will appear, which we will have to edit as follows:
The next step will be to save the changes, close GRUB and update it by executing the sudo update-grub command. Once this is done, we restart the computer and we will have IPv6 disabled.
In this way, problems to access the WAN and other types of issues related to an incorrect IPv6 configurations will be avoided.
Source: Redes Zone.