I have a TG582n with USB on an ADSL line.
The versions of firmware supplied by Plusnet that work with my setup are listed below.
Using the setup wizard the only version that is IPv6 ready “out of the box” is 10.2.0.B
If required an IPv6 ping responder can be enabled via the CLI using the following commands.
service system ifadd name=PINGv6_RESP intf=Internet
service system modify name=PINGv6_RESP state=enabled
saveall
I would therefore think that it is a straightforward  matter for Plusnet to roll out IPv6 enabled versions of firmware for the various models of TG582n and ADSL / FTTC.


8.4.4.J No IPv6 support
10.2.0.B MUST use the setup wizard, if you just change the username & password then IPv6 is NOT enabled.
10.2.1.8 IPv6 disabled by default and still disabled after using setup wizard
10.2.2.9 As for 10.2.1.8
Although the versions below are listed and being for FTTC, the first step of the setup wizard prompts for FTTC or ADSL.
10.2.5.2 As for 10.2.1.8
10.2.5.2.EO As for 10.2.1.8
10.2.5.2.FO As for 10.2.1.8