HELP: "This site can't be reached" from cellular networks

I recently started getting complaints from customers that they can't see our website (https://idealagent.com) which is hosted on a linode running Apache. This seems to be limited to cellular networks (T-Mobile) and some ISP's. I can duplicate the issue from my phone while not connected to WiFi. My home ISP can access the site just fine and if my phone is connected to WiFi it has no problems accessing the site as well. If I refresh the page many times, it will sometimes render the page but continuing to refresh and the issue returns.

![](" /> ~~Apache logs do not show any issues or 404's.

Any ideas what might cause this? Any ideas for diagnosing the cause?~~

2 Replies

It looks like you don't have Apache configured to listen over IPv6, while having AAAA records for your domain.

IPv4 looks exactly as you would expect:

$ dig A idealagent.com +short
45.79.211.196

$ 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[1] and restart Apache, or remove your AAAA records and not advertise IPv6 for that domain.

[1] https://httpd.apache.org/docs/2.4/bind.html

Thank you very sjacobs! That was it exactly! Very much appreciated!

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