modern operating systems have ipv6 support out of the box. so it likely is your ISP or the router. Even if the ISP supports ipv6 they might only roll it out to

modern operating systems have ipv6 support out of the box. so it likely is your ISP or the router. Even if the ISP supports ipv6 they might only roll it out to new customers. Beware though, some ISPs may switch to CGNAT via DS-Lite for IPv4 when they change you to a IPv6 setup.