I try to set static leases for my computer in OpenWRT. I entered IPv4 address (192.168.64.100) and MAC address of my NIC and it works flawlessly. I also tried to set static lease for IPv6, so I entered DUID and IPv6-Suffix (100), but this does not seem to work as IPv6 addresses of my computer stayed the same as they had been before I tried to enforce static lease.
I am running 19.07.1 based port of OpenWRT (FriendlyWRT) on Nanopi R2S. My client, I believe is DHCPv6 capable (Windows 10). It is also shown (in LUCI) that there are two Active DHCPv6 Leases for my computer, but of course they are different than the one set in Static Lease configuration (suffix is for both of them 431 and not 100 as set). I disconnect/restart both client and router, the suffix for IPv6 addresses always stays 431.