FAQ : Connectivity (Tunnels and Subnets) : My IPv6 is random and changes often. Why?
My IPv6 is random and changes often. Why?
Several people have commented on this behavior in our Forum. Please read up on this one for example. The bottom line is that when you enable IPv6 on your Windows machine, the kernel will change addresses to keep you anonymous on the local segment. If you want to use a static address or a non-changing EUI64 address, you'll have to disable these privacy features. Please read up on the privacy extensions in RFC 3041. Various other operating systems also have this feature, but generally have it disabled per default.
To disable it on Windows, use:
netsh int ipv6 set privacy disabled