Stubby for DNS over TLS IPv6

My ISP recently started IPv6 services, I can connect to ipv6 sites.
The current Network topology is an Archer C5400 As the primary router, and a custom OpenWRT build running on TPLink WR841N with a static IPv4 address acting as the DNS server using stubby.

Now I want to use it for the IPv6 queries to but can't seem to be able to configure OpenWRT to a static IP for IPv6 properly.

Can somebody help me with the configuration?