The local ISP I use in my holiday home, Teleservice Skåne, doesn't offer native IPv6 to us lowly ADSL customers. However, they do operate a 6rd gateway! This configuration in my OpenWRT's /etc/config/network made all the difference:

config interface wan6
        option proto '6rd'
        option peeraddr '85.30.128.12'
        option ip6prefix '2a02:83::'
        option ip6prefixlen 32

Ta-da! Thanks, Philip @ Teleservice!

Ask your local ISP if they can do the same!