I have been running a he.net tunnel on a Linux machine as the gateway for a small network for a few years. A delegated /64 is in use on the LAN and has ran without care and feeding for a long time. When a Windows 10 client was added to the LAN, it refuses to work on ipv6. After extensive troubleshooting it appears to be something to do with the default gateway, especially when I compare routing tables on Windows 8 clients (which can access the IPv6 Internet).
On Windows 10, the routing table looks like:
C:\WINDOWS\system32>route print -6
Active Routes:
If Metric Network Destination Gateway
2 266 ::/0 fe80::250:56ff:fe00:1
2 26 ::/0 fe80::10
On Windows 8, the client works fine with routing like:
C:\>route -6 print
Active Routes:
If Metric Network Destination Gateway
4 261 ::/0 fe80::250:56ff:fe00:1
On the Windows 10 machine access to the ipv6 net works if I manually add a static default route (which would have a smaller metric.)
Why is Win10 adding the gateway fe80::10 and how can I get rid of it? It seems to be causing the problem. When I try to remove it with route DEL, Windows says "OK" but does not remove it.
Any ideas? This is driving me nuts.