Disabled ipv6: Made a backup of /etc/default/grub and then edited it (as root). Looked for the line of the system-boot: GRUB_CMDLINE_LINUX_DEFAULT="..." Add the option "ipv6.disable=1" to that line, so that it looks something like this: GRUB_CMDLINE_LINUX_DEFAULT="... ipv6.disable=1" Of course, there were lots of other options before that in that line (symbolized here by the three points). When ready, I did: grub2-mkconfig -o /boot/grub2/grub.cfg That wrote the options to the bootloader (GRUB2). After a reboot, ipv6 was disabled.