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Urgent: False Positive block by BT Web Protection (ERR_SSL_VERSION_OR_CIPHER_MISMATCH)

Francisco — Wed, 04 Mar 2026 20:23:58 GMT

Hi everyone and Moderator, We are experiencing a severe False Positive issue with BT Web Protection. Our UK customers using BT broadband are unable to access our website: pigeons.mercasystems.com (including our main domain mercasystems.com and all other subdomains). The browser returns an ERR_SSL_VERSION_OR_CIPHER_MISMATCH error. This occurs because the BT filter is intercepting the secure handshake, even though our server has a perfect A+ rating on Qualys SSL Labs. We have verified our reputation on McAfee/Trellix TrustedSource (the provider for BT security), and the results are: Reputation: Minimal Risk Categorization: Online Shopping Web Reputation: Trustworthy (92/100) History: 151 months old (Established) Our server IP (165.22.200.204) is also marked as Benign with no threats found. There is no technical or security reason for this block; it appears to be a local BT network misconfiguration. Could a moderator please escalate this to the security team to have mercasystems.com and its subdomains whitelisted? I am attaching the evidence from TrustedSource and the error screen. Thank you for your assistance

Re: Urgent: False Positive block by BT Web Protection (ERR_SSL_VERSION_OR_CIPHER_MISMATCH)

Kimberlin — Thu, 05 Mar 2026 09:00:28 GMT

@Francisco Are you a BT residential customer or are you a BT Business customer?

If the latter, you need to contact BT Business.

You are a US based company?….

Re: Urgent: False Positive block by BT Web Protection (ERR_SSL_VERSION_OR_CIPHER_MISMATCH)

Alex_H — Thu, 05 Mar 2026 09:46:23 GMT

Hi @Francisco,

Welcome to the BT Community

I have passed your message onto our web categorisation team to take a further look into your domain. We will let you know when we receive an update from them.

Alex

Re: Urgent: False Positive block by BT Web Protection (ERR_SSL_VERSION_OR_CIPHER_MISMATCH)

Francisco — Thu, 05 Mar 2026 15:41:32 GMT

Thank you very much Alex. This matter is truly causing us many inconveniences with our UK customers who are BT users. I hope you can resolve this issue as soon as possible. Best regards Francisco

Re: Urgent: False Positive block by BT Web Protection (ERR_SSL_VERSION_OR_CIPHER_MISMATCH)

Francisco — Thu, 05 Mar 2026 15:56:23 GMT

Yes, our main office is located in the US. Best regards Francisco