How to configure rdnss?

My LAN servers are mainly in IPv6, configured with SLAAC.
Some servers also have IPv4 connectivity.

Is there a way to announce IPv6 DNS servers via RDNSS ?
radvd is deprecated by OpenWRT.

My /etc/config/dhcp:

config dhcp 'lan'
    option interface 'lan'
    option start '100'
    option limit '150'
    option leasetime '12h'
    list dhcp_option 'option:mtu,1472'
    list dns ''
    list dns '2a01:e34:eebf:b5d0::1'
    list domain ''
    option dhcpv6 'server'
    option ra 'server'
    option ra_management '0'


This should do the trick. At least it works for me like this. See example here - under „Použití Google Public DNS64“ heading.

Indeed. I see the rdnss advertisement in the icmp6 packet! The issue must be by the client.
Thank you.