As I’ve mentioned before .. this is probably the outcome of either your IP being blocked, or more likely - the use of something like a VPN and that IP is blocked. Other options include something like your local network or ISP blocking 0x0.
I can very easily trigger this exact same ‘error’ on 0x0, or my own website, or countless others, by switching my VPN to a different endpoint.
The actual error message is produced by a malformation in the connection - in reality the connection is refused but returns a string when the browser expected the SSL cert.