The 3002 does not join the NT domain, it merely uses an NT domain account to verify the username/password that you have configured in it.
If the tunnel is coming up then that part of the config is working OK. Are you using NEM or client mode. If NEM, make sure your internal network behind the 3005 has a route to the network behind the 3002, and that that route points to the private interface of the 3005. similarly with client mode, make sure the internal network has a route to the VPN pool of addresses that points to the 3005.
From a host behind the 3002 can you ping the private interface of the 3005? This rules out any routing issues on your internal network. If you can, but can't ping any further, then you have a routing issue. If you can't ping the private interface, and the tunnel is up, then you probably have a filtering issue somewhere. Check under Monitoring - Sessions on the 3005 for the 3002 tunnel stats, are you getting RX packets (from the 3002) and TX packets (to the 3002) incrementing when you ping?
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...