Site not loading on AT&T

I recently started experiencing an issue with one of my sites where it doesn’t load if on cellular AT&T network. I have about 80 site all on the same server, all the same IP address, all with CloudFlare service, all of them load but one when connected to AT&T. WiFi, they all work fine.

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Could it be due to SSL settings at Cloudflare dashboard for that one? (maybe it is on Full, while you use Flexible? - just guessing is it because of Cloudflare or the server serving, or actually the ISP thing like DNS propagation if recently modified? …)

Does that one have correctly entered value for the given Cloudflare nameservers?

Have you tried on some other network like mobile data, but not AT&T?
Any recent AT&T outages or issues reported?

What error do you get?

May I ask what do you get, if the domain is actually reachable, if you visit https://www.yourdomain.com/cdn-cgi/trace URL?

Hm …

No changes have been made to DNS or SSL. It has been working fine, just recently stopped. The trace program won’t even load over cellular, connected to WiFi it works fine. It’s not isolated to my phone either, I’ve had customers call and complain.

Disabling the Proxied A record under DNS, allows AT&T cellular traffic to connect to the site.

Exact same problem here. I have also tried removing the domain from my cloudflare account and adding it back again, hoping to get a new cloudflare IP address and/or nameservers, but the NS and IPs are the same as before and the issue persists.

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