BT DNS returns NXDOMAIN for our business domain - all BT customers affected, works on every other IS

[briantruongau]

Hi all,

Hoping a moderator can help escalate this one, as it's costing us customers.

Our web app at builder.printerp.ai cannot be reached by any of our customers on BT broadband. On every other UK ISP — and on any public DNS — it loads fine. We've confirmed this across multiple separate BT customers on different BT lines.

BT's DNS returns "Non-existent domain":

C:\> nslookup builder.printerp.ai
Server:  hub.home.arpa
Address: 192.168.1.254

*** hub.home.arpa can't find builder.printerp.ai: Non-existent domain

This isn't a caching issue — customers have flushed DNS and rebooted their hubs repeatedly over several days with no change.

Here's the part that makes me think it's a filtering false positive:

Other hostnames in the exact same DNS zone resolve perfectly on the same BT connection, at the same moment, returning identical IP addresses:

api.printerp.ai            104.21.66.237, 172.67.165.220   -> resolves OK
builder.printerp.ai        104.21.66.237, 172.67.165.220   -> NXDOMAIN

Same nameservers, same IPs, same zone. Only that one hostname fails, and only on BT. If a customer sets their DNS to 8.8.8.8 it works instantly — so this is happening at BT's resolvers, not in our DNS config.

For what it's worth, the domain is clean everywhere I've checked:

• Google Safe Browsing — "No unsafe content found"
• Spamhaus — "no issues"
• Netcraft — no fraud or malware indicators

We're a legitimate B2B business — the site is a tool UK print and apparel companies use to prepare artwork and manage print orders. We're BT Business customers ourselves.

I've emailed [email protected] as well, but posting here in case a moderator can help move it along.

Is there anything else I can provide to get this looked at?

Thanks.

[BethM]

Hi briantruongau

Thanks for the information provided. For DNS and website categorisation concerns, the appropriate team is the Safe Browsing team via [email protected]. 

We appreciate you taking the time to report the issue and hope you're able to get a swift resolution from the team.

[briantruongau]

I sent an email to [email protected]. 
Many thanks. 
Brian

[briantruongau]

Hi @BethM — an update, and unfortunately not a good one.

I emailed [email protected] on 2 September as you advised, and again on 3 September. I have had no reply to either — no acknowledgement, no case reference, nothing. I also raised it via BT Business live chat, where the agent didnt understand the problem and couldn't issue a reference number.

The site is still unreachable for every BT customer, and still resolves normally on every other UK ISP.

Worth noting: the domain had been incorrectly auto-classified upstream as "DGA Domains", a malware category. That has since been corrected at source — Cloudflare Radar now shows printerp.ai as "Artificial Intelligence / Technology" with a Low security rating and both incorrect categories removed. So the basis for the block is gone from the upstream data. BT's block is not.

I've now sent a third email asking for it to be logged as a formal complaint.

@BethM — I appreciate you pointing me in the right direction, and I'm not asking you to fix it personally. But is there any way to get a human to look at that mailbox? Three emails over three days with zero acknowledgement, on a route BT publicly designates as the correct one, is not a working process. A UK business is losing revenue daily and every customer affected is a BT customer.

Happy to supply anything that helps: nslookup output from affected customers, Cloudflare Radar screenshots, reputation checks from Google Safe Browsing, Spamhaus and Netcraft.

Thanks.

[briantruongau]

Hi @BethM — an update, and unfortunately not a good one.

I emailed [email protected] on 2 September as you advised, and again on 3 September. I have had no reply to either — no acknowledgement, no case reference, nothing. I also raised it via BT Business live chat, where the agent didnt understand the problem and couldn't issue a reference number.

The site is still unreachable for every BT customer, and still resolves normally on every other UK ISP.

Worth noting: the domain had been incorrectly auto-classified upstream as "DGA Domains", a malware category. That has since been corrected at source — Cloudflare Radar now shows printerp.ai as "Artificial Intelligence / Technology" with a Low security rating and both incorrect categories removed. So the basis for the block is gone from the upstream data. BT's block is not.

I've now sent a third email asking for it to be logged as a formal complaint.

@BethM — I appreciate you pointing me in the right direction, and I'm not asking you to fix it personally. But is there any way to get a human to look at that mailbox? Three emails over three days with zero acknowledgement, on a route BT publicly designates as the correct one, is not a working process. A UK business is losing revenue daily and every customer affected is a BT customer.

Happy to supply anything that helps: nslookup output from affected customers, Cloudflare Radar screenshots, reputation checks from Google Safe Browsing, Spamhaus and Netcraft.

Thanks.