My ISP provides a /64 IPv6 prefix. The OpenWrt router receives a valid IPv6 address and is reachable from the outside via IPv6. However, a Windows laptop on the LAN has intermittent IPv6 connectivity.
Running ipconfig on the laptop shows both a global IPv6 address (starting with 2) and a temporary IPv6 address. Despite this, online IPv6 tests fail, and trying to ping ipv6.google.com does not work (DNS resolution or connectivity failure).
I've already applied the relay mode fix described here:
As I do get IPv6 connectivity on the Windows laptop for a while before it stops working, could this indicate an issue on the ISP side — perhaps with the lease time or prefix delegation renewal?
I’m trying to understand where the issue might be — OpenWrt configuration, Windows behavior, or something on the ISP side. I also have Linux and Android devices on the network, but I haven’t tested them as consistently, so I'm not sure if they’re affected in the same way.
Right now, I have IPv6 connectivity through my OpenWRT router. I can successfully reach and pingipv6.google.com from both the router’s diagnostics page and a Linux machine on the network. However, my Windows laptop currently does not have IPv6 connectivity.
When I run the ipconfig command on the Windows laptop, it shows what appears to be a valid IPv6 address with the same /64 prefix as the router and the Linux machine. Despite this, I'm unable to reach ipv6.google.com from the laptop.
What I've noticed is that the IPv6 connectivity on the Windows laptop is inconsistent. Sometimes it works, and then, without making any changes to the Windows settings or the OpenWRT router, it stops working. Later, again without any configuration changes, it starts working again. So the IPv6 connection on Windows is unreliable, even though the address itself seems valid.
As for the Linux machine, it generally appears to maintain IPv6 connectivity, but I don't monitor it frequently enough to be sure if it ever loses it intermittently as well.