Maybe someone can chime in to share some experiences as I can't find what is wrong here...
We have several VLANs used on internal networks, each of them with a IPv6 /64 network configured with RA. RouterOS 6.49.6 on a CCR.
Many machines are connected to those networks and their IPv6 works just fine (Android, iPhone, Chromebook etc).
But now we are rolling out some Windows devices (stupid move, I know...) and I encounter difficulties with IPv6:
Just after boot I get IPv6 connectivity. Can ping IPv6 addresses internal and external to the company just fine.
There is one exception: I cannot ping the local router address on the network the Windows PC is connected to. But I can ping other addresses of the router.
However, when I leave the system at rest for only a couple of minutes, IPv6 connectivity dies. Cannot ping any address that was OK before.
At first it simply does not work anymore, but after waiting some more time I often see the default route (::/0) disappear from "route print".
What can be going on here? I have fiddled with the different times in /ipv6 nd but it has not changed a thing, and the time until it fails is nowhere
near any of those times. And it works perfectly on Linux/Android and BSD(Apple) devices!