I am getting IPv6 address over Wireguard. It is only /128 IPv6 address. So I am doing NAT6. Clients on the network gets private IPv6 address. However, they are able to reach IPv6 address. Running ipv6-test.com, you are able to reach IPv6 websites. However, on Windows, the network adapter will mark IPv6 as No Internet Access and browser will prefer IPv4 over IPv6 eventhough it is fully capable of reaching IPv6 addresses. Is there any configuration on OpenWRT I could do to make it prefer IPv6 and have Windows think there is internet access on IPv6?
The IP version priority is determined based on the address scope and connectivity by the client OS.
The proper way to make the client prefer IPv6 is to delegate it a public IPv6 address.
Otherwise, you can only utilize some dirty hacks which may result in more serious drawbacks.