Software is Preventing Firefox From Safely Connecting to This Site

Are you using SSL /TLS inspection rules? Did you install the cerificate in Firefox?

where do i find the self signed cert for the sophos firewall, if i can get it, i will install on my firefox as a trusted root CA

i have no idea if its an endpoint issue or sophos firewall issue

Please read this: support.sophos.com/.../KB-000035645

that did not work, maybe its endpoint then doing this instead of the firewall?

Does the traffic hit the correct FW rule? Can you see expected entries in the SSL/TLS log?

its def endpoint, as when i disable web control, it works, i get no cert error

going to google it now but if anyone can help much appreciated

thanks,

rob

Let me know if the following article applies to the issues you're experiencing.
- Firefox may experience issues if DNS over HTTPS is enabled

no DNS over HTTPS unticked/off

Do you have any additional details on what error is displayed? Could it be "SEC_ERROR_UNKNOWN_ISSUER"? 

The endpoint is also able to perform TLS/SSL decryption of HTTPS websites. I suggest checking if this is enabled in your Threat Protection Policy. This will remain disabled if you have "Use recommended settings" checked.