Like this for instance:
option dhcp6.name-servers = 2a03:7520:4c68:1::1000
That's for the server, not the client. My server is in my pfsense
firewall/router and works fine. The issue is my ThinkPad, when
running Leap, only uses DHCPv4 to get the DNS server address. Other
devices have used RDNSS for years without issue. I just set up the
DHCPv6 server yesterday, to see if it would work for this. I can
use IPv4 but not IPv6.
I just did a test and did a packet capture for port 67 and 546. I
get both DHCP and DHCPv6 and both show the appropriate addresses,
but only the IPv4 address is used.