I opened an support ticket on getting IPv6 Virtual IP that will allow me to place a URL to internal IP address for web servers.  2.5.2021, Fortinet L2 engineer wrote up a NFR for my URL Virtual IP request for IPv6.    FutureCon is looking into a IPv6 talk.  I moved the Ubuntu DHCP and DHCPv6 back to the Fortinet because IA-NA and IA-PD need DHCPv6.  

I got rid of AT&T.  They gave me only one /64 PD.  Against all better judgment I switched to Comcast.   doubled my download speed and 1/3 the price.  Bought a Arris SB8200 3.1 modem.  

config system interface
  edit "wan2"
    config ipv6
      set ip6-mode dhcp
      set ip6-allowaccess ping
      set dhcp6-prefix-delegation enable
      set dhcp6-prefix-hint ::/60
    end
  next
end
config system interface
  edit "lan"
    config ipv6
      set ip6-mode delegated
      set ip6-allowaccess ping https ssh
      set ip6-send-adv enable
      set ip6-other-flag enable
      set ip6-upstream-interface "wan2"
      set ip6-subnet ::1/64
      config ip6-delegated-prefix-list
        edit 1
          set upstream-interface "wan2"
          set autonomous-flag enable
          set onlink-flag enable
          set subnet ::/64
          set rdnss-service default
        next
      end
    end
  next
end

How do you auto assign all your LAN interfaces to the next subnet?  You take the code above and modify the config ipv6 – set ip6-subnet.

Here is an example I used from my old AT&T stuff.  It is no longer in use.  This is the /60

2600:1702:980:25e0:/60
1st subnet: 2600:1702:980:25e0
2nd subnet: 2600:1702:980:25e1
3rd subnet: 2600:1702:980:25e2

16th subnet: 2600:1702:980:25ef

First subnet:

set ip6-subnet ::1/64


Second subnet

set ip6-subnet ::1:0:0:0:1/64

Third subnet

set ip6-subnet ::2:0:0:0:1/64

Fourth subnet

set ip6-subnet ::3:0:0:0:1/64

Fifth subnet

set ip6-subnet ::4:0:0:0:1/64

Sixth subnet

set ip6-subnet ::5:0:0:0:1/64

Seventh subnet

set ip6-subnet ::6:0:0:0:1/64

Eighth subnet

set ip6-subnet ::7:0:0:0:1/64