The error message appears when IPv6 is disabled on Security Gateway running Gaia OS.
By default, the IPv6 module is located in the /lib/modules/2.6.18-92cpx86_64/kernel/net/ipv6/ipv6.ko
When IPv6 is disabled, the IPv6 module should not be loaded. Therefore, when IPv6 is disabled, the path to IPv6 module is changed to /lib/modules/2.6.18-92cpx86_64/kernel/net/.ipv6/ipv6.ko (note the dot in the folder's name - ".ipv6")
This message is printed because the module is not found.