HELP: "This site can't be reached" from cellular networks
Any ideas what might cause this? Any ideas for diagnosing the cause?~~
IPv4 looks exactly as you would expect:
$ dig A idealagent.com +short 18.104.22.168 $ curl -4 -sIL https://idealagent.com | grep HTTP HTTP/1.1 200 OK
But IPv6 is failing to return a response:
$ dig AAAA idealagent.com +short 2001:4860:4802:32::15 2001:4860:4802:34::15 2001:4860:4802:36::15 2001:4860:4802:38::15 $ curl -6 -sIL https://idealagent.com | grep HTTP $
You can confirm this by running:
$ netstat -tlpn
After running that, most likely, you will see "0.0.0.0:80" and '0.0.0.0:443" in the output, which is IPv4. If IPv6 is listening, there will be ":::80" and ":::443" listed in the "Local Addresses" column.
To get it working for those customers, you could either add the required "Listen" arguments to your Apache config for IPv6 and restart Apache, or remove your AAAA records and not advertise IPv6 for that domain.