/boot/grub/grub.cfg
читаем
grub.cfg 1014/6990 14%
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#
в /etc/default/grub правим
GRUB_CMDLINE_LINUX_DEFAULT=»ipv6.disable=1 elevator=noop»
sudo update-grub