DHCPv6 instance for each IPv6 enabled interface. Bug?

[JasMan]

Hi all,

I had an issue after my ISP changed the IPv6 prefix of my Internet line. None of my clients was able to establish a IPv6 connection.

I did a packet capture and noticed, that my clients received always four DHCPv6 advertisments in respone of their solicit. Three of them contained the previous IPv6 address with the old prefix. Only one contained the new address/prefix.

The clients requested the address of the first advertisment, which was always the old address. The request was (of course) denied by OPNsense, because of the wrong prefix (status code 13, NotOnLink). Result: no IPv6 connection.

I was wondering why the clients got always four advertisments. Then I noticed that the process list showed four DHCPv6 instances. That's the same number of enabled IPv6 interfaces on my OPNsense (one static, three with DHCP enabled).
I decided to disable IPv6 on one of the interfaces, and after that the clients received "only" three advertisements.

I'm pretty sure that this is a bug, because I see only one DHCPv4 instance for my five IPv4 interfaces. I guess that only one DHCPv6 instance was notified about the new prefix, and the other ones used the old one. After I rebooted OPNsense, all advertisments contained the new prefix/address.
 
If I#m right and this is a bug, I'm wondering why nobody else has noticed this before, because many users would have the same issue then after a prefix change.

I would like to be sure that this isn't a configuration issue. Therefore, could somebody please check if her/his OPNsense has also more than one DHCPv6 instance running, if more than one interface uses IPv6? Would be great :-)

Thank you.
Jas