Hello,
There is a well-known place to find out if Your chosen IPv6 address is forwardable or not:
http://www.iana.org/assignments/iana-ipv6-special-registry/iana-ipv6-special-registry.xhtml
| 2001:db8::/32 | Documentation | [RFC3849] | 2004-07 | N/A | False | False | False | False | False |
You have to pick another IPv6 address range for Your tests.
HTH
Thx
Alex