Created attachment 576451 [details] Debug output. I have a MacBook Pro 8,3 with BCM4331 wireless. This has been working nicely for a while. But in the last couple of weeks it's stopped working properly at home, although it seems fine elsewhere. The problem is that it keeps disconnecting every 5 minutes, which is what I have AdvValidLifetime set to in radvd.conf. See from about line 4581 in the attached log.
NM and the kernel are fighting over routes, causing the kernel to end up dropping RAs, causing the DNS server data from your first RA to eventually time out, causing NM to drop the connection and try again. *** This bug has been marked as a duplicate of bug 785772 ***