howto: IP passthrough to edgerouter: enable IPv6

I recently subscribed to AT&T gigabit and discovered that the Ubiquiti wizard defaults failed to provide ipv6 connectivity.

I spent a fair amount of time searching online, and I finally came across a link that worked for me: https://www.reddit.com/r/Ubiquiti/comments/m1jkuc/anyone_doing_vlans_on_att_fiber_and_ipv6_on_udm/

The link was specific to an EdgeRouter 4, but it worked perfectly for my EdgeRouter Lite running v2.0.9-hotfix.4.  I have eth0 connected to the bgw320-505, eth1 and eth2 are separate ipv4 subnets

I made these changes using the Config Tree:

1. interfaces / ethernet / eth0 / dhcpv6-pd / pd / 0 / interface / eth2 : deleted
2. interfaces / ethernet / eth0 / dhcpv6-pd / pd / 0 / interface / eth1 : blanked out prefix-id, changed prefix-length to /64
3. interfaces / ethernet / eth0 / dhcpv6-pd / pd / 1 : added with prefix-length /64
4. interfaces / ethernet / eth0 / dhcpv6-pd / pd / 1 / interface : added eth2
5. interfaces / ethernet / eth0 / dhcpv6-pd / pd / 1 / interface / eth2 : set host-address to ::2, blank prefix-id, set service to slaac

Eth1 and eth2 end up with 2 separate ipv6 subnets.  From the bgw320:

IPv6 Delegated Prefix Subnet: xxxx:xxxx:xxxx:801e::/64 , xxxx:xxxx:xxxx:801f::/64

Thought I would share.