Anyone else seeing IPv6 going up and down constantly?

I've had the 2 gig fiber plan for about a year and a half now and around a year ago it started handing out v6 addresses but they never worked. It would pass traffic for about 5 minutes then stop. My router would notice this, invalidate the v6 route and then everything would work fine with only v4 traffic.

For the last few days however, I've noticed lots of stalling webpages and sudden slow-downs. I started looking into it today and it looks like the IPv6 traffic is just going in an out every few minutes. It seems to pass traffic just long enough to poison my router's DNS resolver with v6 entries, then stop passing traffic causing everything to stall. If I disable v6 everything goes back to normal.

Is anyone else seeing this behavior? Are there any frontier-specific changes I need to make to get IPv6 working? Currently I'm just turning on DHCPv6 and taking whatever I'm assigned.