To disable IPv6 on Linux, open /etc/sysctl.conf and ensure that it contains the below listed lines with a value of "1".
[no-highlight]net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1[/no-highlight]
Next, run "sysctl -p" in a terminal with Root privileges. That command will refresh the settings without needing a reboot or logout.