Ubuntu18 disable IPv6

• Edit /etc/sysctl.d/99-sysctl.conf and add the following lines to the end of the file

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

• Reload values

sysctl -p

Reboot bug

• create a new file /etc/rc.local

#!/bin/bash
# /etc/rc.local
# Load kernel variables from /etc/sysctl.d
/etc/init.d/procps restart
exit 0

• Change permissions to this file

chmod 755 /etc/rc.local