TLDR (click to expand) It was a setting on my Adguard Home DNS which disables IPv6 by default.

I’ve been using ACT broadband for my home network for quite a while and they did not support IPv6 for quite some time. A few years back I contacted their support, they confirmed they are slowly rolling it out for users in Chennai. I was one of those users and I enabled IPv6 in my router and it worked without any issues. I just did a quick test and just forgot about it.

There are lot of benefits in enabling IPv6 in your network like reduced latencies, better P2P connections due to the lack of NAT traversals, SLAAC, etc.

I was testing my network connectivity due to a recent desk upgrade and noticed that ping google.com succeeded, but ping6 google.com failed. Weird, I thought my ISP might have disabled IPv6 again. I confirmed ISP connectivity via IPv6 into my router’s admin portal. Then I shouldn’t have a problem connecting to IPv6?

Maybe an issue with the device? I checked my macOS network settings and I have IPv6 allowed there as well.

macos settings

I logged into the raspberry pi connected over LAN to my router and noticed the same issue there. Since I’m running my own DNS server, I checked my router’s DNS settings for IPv6 DNS server address and cross-verified the ip address with my pi’s ethernet interface.

router IPv6 DNS settings

Maybe a DHCP issue with IPV6 DNS? To rule it out, I wanted to try pinging an IPv6 address directly - maybe google - and when I tried running dig AAAA google.com, no results from the DNS. Obviously, google will support IPv6 so I knew something was wrong with my DNS server. I then realized moving to Adguard Home DNS last year. When I checked Adguard Home’s DNS server settings, I found this small toggle that I overlooked.

Adguard DNS settings

I unchecked that setting, saved and now I’m rocking IPv6 again.

$ ping -4 google.com -c 5
PING google.com (172.217.24.110) 56(84) bytes of data.
64 bytes from lcmaaa-ap-in-f14.1e100.net (172.217.24.110): icmp_seq=1 ttl=118 time=1.58 ms
64 bytes from lcmaaa-ap-in-f14.1e100.net (172.217.24.110): icmp_seq=2 ttl=118 time=1.53 ms
64 bytes from lcmaaa-ap-in-f14.1e100.net (172.217.24.110): icmp_seq=3 ttl=118 time=1.52 ms
64 bytes from lcmaaa-ap-in-f14.1e100.net (172.217.24.110): icmp_seq=4 ttl=118 time=1.64 ms
64 bytes from lcmaaa-ap-in-f14.1e100.net (172.217.24.110): icmp_seq=5 ttl=118 time=1.56 ms

--- google.com ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 10ms
rtt min/avg/max/mdev = 1.519/1.565/1.637/0.065 ms

$ ping -6 google.com -c 5
PING google.com(maa05s16-in-x0e.1e100.net (2404:6800:4007:817::200e)) 56 data bytes
64 bytes from maa05s16-in-x0e.1e100.net (2404:6800:4007:817::200e): icmp_seq=1 ttl=118 time=1.61 ms
64 bytes from maa05s16-in-x0e.1e100.net (2404:6800:4007:817::200e): icmp_seq=2 ttl=118 time=1.56 ms
64 bytes from maa05s16-in-x0e.1e100.net (2404:6800:4007:817::200e): icmp_seq=3 ttl=118 time=1.56 ms
64 bytes from maa05s16-in-x0e.1e100.net (2404:6800:4007:817::200e): icmp_seq=4 ttl=118 time=1.66 ms
64 bytes from maa05s16-in-x0e.1e100.net (2404:6800:4007:817::200e): icmp_seq=5 ttl=118 time=1.60 ms

--- google.com ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 12ms
rtt min/avg/max/mdev = 1.557/1.597/1.661/0.063 ms