DHCPv6 missing clients in IPv6 Lease table

Hi,

because I am not able find way how to submit support ticket about UTM9 then I try to ask here.

I have bit weird problem with DHCPv6 server, I set it up and it works properly, clients grab addresses and it works well, problem is with Lease table entries, actually I just testing IPv6 then I set up only 3 clients, all 3 clients get address but in Lease table I see only 2 clients, 3rd client is missing in that table but he have valid address and he periodically renew lease (it is Win10).

I looked also in file dhcpd6.leases and I see that client there but actually it have 2 entries, both active and with some weird looking ia-na.

I already try to stop dhcpv6 server, remove that lease file and start server again but nothing was changed.

With this client I have also another odd problem, if I set preferred-life and max-life to different times this client fail to renew IP at preferred-time and after short time it mark IP as "deprecated", only way is use ipconfig /renew6 or wait until max-life is reached. I looking in win logs and in Dhcp logs and seems client try to renew IP, he get response from dhcp but for unknown reason he ignore that reply. If I set both times to same value everything working well and no more "deprecated" IP.

Have anyone idea what is wrong ?

Thanks for any idea

/Tomi