IPv6 PD L2TP

Hi.

I am playing with IPv6 on my home network. I have MT1 where I get /56 prefix from ISP. I added on this MT a pool /56 with prefix-length 64.

To MT1 there are two other Mikrotiks connected via L2TP (MT2 and MT3).

On MT1 in L2TP profile I added DHCPv6 PD Pool and selected earlier added pool.

On MT2 and MT3 I added DHCP6 Client on L2TP with prefix selected.

Why do I get the same prefix on both MT2 and MT3?

RouterOS 7.18.2 on MT1

RouterOS 7.20.2 on MT2

RouterOS 7.20.6 on MT3

After upgrading all MTs to 7.22.3 it started to work as expected… Maybe reboot or maybe upgrade helped.