Comment 12 for bug 1101825

I believe I am affected by this issue as well. I have a Google WiFi device as a router, and everything works well for the first few days, with the link-local address used on the Google WiFi's RA used as the IPv6 default route.

After a couple of days however, the Google WiFi device changes its link-local address (for some reason) on the LAN subnet, and although an RA goes out with this new link-local address, NetworkManager still hangs onto the old default route (which is marked "static" as well) and as such I lose IPv6 connectivity to the outside world. I have to run "nmcli conn up Ethernet" to force NM to delete the old default route and use a the new one.

Also, if I manually "ip -6 replace default ..." leaving the line otherwise intact as it comes from NM, changing only "proto static" to "proto ra", as soon as the Google WiFi sends another RA, NM re-writes the default as "proto static"- yet does NOT update the actual "via" link-local address to the one the RA came in on.