When you create an image of a Linux server that is assigned an IPv6 address using DHCP, the server's IPv6 settings are also cloned. As a result, the antispoofing and firewall rules in the configuration are not automatically adjusted so that they are configured for the IPv6 address of the original server. Therefore, before creating an image from a Linux server that is assigned an IPv6 address, make sure that the leases file (e.g. /var/lib/dhclient/dhclient6-eth0.leases or /var/lib/dhclient/dhclient6.leases) is always removed.
Please note: This does not apply if the IPv6 address is statically assigned. In this case, no leases file will be created, so the IPv6 settings will not be cloned when creating an image.