[neutron]IPv6 Prefix Delegation could not be activated in newest version Neutron

Hi All, I'm working on validate the IPv6 PD in newest Neutron. What I want is to offer the Global Unified address to the VM and I find PD is the good solutions for me.

I follow the guide *https://docs.openstack.org/neutron/latest/admin/config-ipv6.html https://docs.openstack.org/neutron/latest/admin/config-ipv6.html *to setup PD and dibbler-server and devstack, but I find I could not to trigger the PD process. *The Dibbler server print nothing when attach the Subnet to router has external gateway.* All procedure has recorded to the bug: https://bugs.launchpad.net/neutron/+bug/1844123.

Thanks for your action and help in advance!