I'm running a small business website that suddenly became inaccessible for anyone using an AT&T cellular network. Personally, on my AT&T phone, it seems like the connection just drops. However, I can access the site without issues if I'm on Wi-Fi or using a VPN. When I run a DNS lookup, it resolves correctly, and I can SSH into the server using the IP address. I've tried some trace tools through a hotspot, but they hindered UDP traffic, which didn't help. The site passes TLS checks and isn't flagged or blacklisted anywhere that I've found. We're quite confused about what's going on. Does anyone have any insight into this?
5 Answers
It might be a firewall issue where AT&T blocks certain ports (like 80 or 443) for specific IP ranges. I’ve seen this happen before with mobile users being assigned IPv6 addresses, while the server wasn’t configured to accept them. You may want to check your server settings and try enabling IPv6 to see if that resolves the problem. As you found later, adding the correct IPv6 listen directive in your Nginx config could be crucial.
It sounds like it could be a DNS issue with AT&T. Since you can access your server directly via its IP address, the DNS resolution might be failing for some reason. It might be worth checking that the DNS cache is updated properly. Sometimes, if a domain's lease time is set too short, DNS records can be outdated before they refresh, leading to connection problems for certain ISPs.
Make sure to check if your website is on any spam or malware lists that AT&T might be using. Although you mentioned it wasn't flagged, it’s worth double-checking just to be safe.
You should verify your server's IP against spam lists. I had a similar situation where my shared hosting's IP was flagged, and it affected connectivity. Even if it seems unrelated, it can cause issues with multiple users.
Hey, I went through something similar! Turns out our old IT head had blocked a range of IPs due to spamming. It was frustrating until we figured it out. If you suspect a similar issue, look into your hosting configurations. It might also help to use your own DNS server while connected to a hotspot to bypass any problems.
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