A common issue we notice is that users who have IPv6 enabled on their VPS have connectivity issues when rebooting. The problem 99% of the time, is the default route for IPv6 traffic is not present. By default, OpenVZ virtualization doesn’t seem to add the default route via the venet device unless specified by the user (unlike IPv4 behaviour).
Type the following command as root:
ip route add ::/0 dev venet0
While the above solution will work, it is not practical as most admins don’t want to manually type this each time they restart network services or reboot their machines.
To ensure the default route is present on boot. Add the following 2 lines of code to the /etc/sysconfig/network file.
This will ensure that your OS will add the default route for IPv6 on boot.