Neutron considers the network address a valid IPv6 address if the owner is a router or is not defined yet [1][2]. If not, the IPv6 address is discharded. [1] https://tools.ietf.org/html/rfc4291#section-2.6.1 [2] https://review.opendev.org/#/c/647484/ Change-Id: I1ddee94bd34182960de8e5261fbc99edc10b6654 Closes-Bug: #1859163