Hi,
About the client and server, if I am not wrong, about 3 years ago ISC dhcp was the only implementation able to configure DHCPv6 clients by their MAC addresses (thing that I needed at work). It is a pity that ISC is giving less love to it. That said, the EOL date is still TBA (https://www.isc.org/dhcp/)
The EOL timeline has now been announced. https://www.isc.org/blogs/dhcp-client-relay-eom/ ---Q1 2022 - We intend to produce an 4.4.3 release, which will declare in its release notes that it is expected to be the last release containing the client and relay components of ISC DHCP. We hope this message will reach any additional active users who are not subscribed to the DHCP-announce or DHCP-users lists.
H1 2022 - After the last update to the client and relay in 4.4.3, we plan to issue ISC DHCP 4.4.4, removing the client- and relay-specific code from the distribution.
--- Bernhard