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I'm unable to reach microsoft.com or apple.com when my router has IPv6 enabled. According to the tool found here https://ready.chair6.net/, neither microsoft.com nor apple.com have AAAA records. I was able to reach google.com which has an AAAA record. What's the real problem. Is it my router, Cox or the websites not having AAAA records?
I'm sticking with IPv4 for now.
Long story short, it's the websites. Not all websites are IPv6 ready. However, when IPv6(AAAA) doesn't work, it should fall back to the IPv4(A) record. The fact that it doesn't sounds more like how IPv6 and DNS is implemented on your local network.
I would suggest trying 2001:4860:4860::8888 for one of your DNS to see if Google DNS works any better. If not, and you don't need IPv6 for anything, I suggest leaving it off.
::edit:: Oops. Didn't know there was a IPv6 Cox problem. Disregard.