Sorry, but DNS guard is always enabled. But I cannot think of a good reason to disable DNS guards. Could you let us know why your DNS administrator thinks it is a good idea to open a known DNS vulnerability?
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...