As far as I know ACS 5.x doesn't accept any special characters (\, /, @) in username field while creating repo and few other customers also faced the same issue. This is not supported with GUI and CLI. Last I checked this on ACS 5.3. You need to use a simple user account without any special character. I'll also check if there is any enhancement request filed to support this.
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...