I have my ISP's router connected  to the Broadband line, and that works as expected.

My 2685 is then configured to use WAN2 ethernet connected and sits behind the ISP's router.

This works just file for IPV4 but I cannot seem to get IPV6 to work.

WAN2 gets an IPV6 address but the DHCP server in the 2685 does not issue an IPV6 address that can be touted to the internet.

Any help / pointers appreciated

Apologies, I don't have time to write a full answer / explanation here, but I do recommend doing some reading on how IPv6 addresses are assigned to LAN clients, this may help you diagnose the problem.

In short, DHCP in the standard sense is often NOT what is used to assign IPv6 addresses. It can be used in some cases, in the form of DHCPv6, but often, SLAAC (Stateless Auto-configuration) is used, whereby the client basically assigns itself an address.

Might point you in the right direction? I don't currently have IPv6 running on my network as my ISP does not provide it, although I have used it on a 2865 in the past.

Thanks for your reply, I had been doing some more reading even after I posted my original question. I eventually found a page that explained things a little differently and I tried what it suggested. Turning on bridge mode for IPV6 seems to have done the trick and its now working as I would expect.

That said Whilst I have read the words on the firewall part of that configuration page, I am not 100% sure if I should click that checkbox or not. Do you have any thoughts or pointers on that?

Could you elaborate slightly as to what 'Bridge Mode' you have turned on? Which menu is this in?

Do you mean the 'Block routing connections initiated from WAN' checkbox?