Run the following to disable IPV6, reverts at reboot
echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
Add the following lines to /etc/sysctl.conf to make change permanent
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
Make active:
sysctl -p