"A DHCPv6 server can be either a stateful or a stateless server. A stateful DHCPv6 server provides both IPv6 address and "other information," such as a DNS server list and a domain name, to hosts. If you are configuring a stateful DHCPv6 server, you configure an address pool"

if you want to make DHCPv6 Server act only as a Stateful server apart from configuring the address pool, you need also to make the Autonomous flag OFF and Managed flag ON

To change the Autonomous flag OFF you need to execute the below command from CPE CLI

admin@Branch-02-cli(config)% set routing-instances Test-LAN-VR protocols router-advertisement interface vni-0/2.0 prefix 2001::/64 autonomous ?

Description: Set/Reset autonomous flag

Possible completions:

  [true]  false  true

 The interface would be your configured DHCPv6 Interface

routing-instance would be your LAN side interface

From Director GUI navigate to Configuration ------ Click on Branch device name -------- Virtual routers ----- Click on routing instance ----- Router Advertisement ------ Add Router Advertisement ----- Add Prefix list ----- Set Autonomous Flag  

Note --- Option in Director GUI is supported only after 21.1.3 releases