Disable IPv6 Debian 8 / Ubuntu
If can’t remove IPv6 on Debain 8 from hosting admin menu, It can disable through terminal
Debian-based/Ubuntu
sudo bash -c 'cat <<EOF >> /etc/sysctl.conf net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1 EOF'
Configure SSH daemon to only listen over IPv4 by running the following:
echo 'AddressFamily inet' | sudo tee -a /etc/ssh/sshd_config
Then Reboot #reboot