[icehawk]

- Is the certificate invalid?

- Was the IP address found, but is returning malformed answers?

- Is it returning nothing at all?

Firefox returns "Your connection is not secure" for the first, and the raw data from the HTTP request for the others. (Or Secure Connection Failed for the second if you try to use HTTPS)

"We’re having trouble finding that site." is only ever given if the browser tries to do a DNS lookup and does not get an answer.

[jevoten]

Having to first get an error message for every other error condition first, to find what this error is about by process of elimination, is not reasonable or informative.