[ameliaquining]

The SSL error is likely from visitors on networks that use network-level blocking of domains that have been flagged as malicious. When visiting such a site over unencrypted HTTP you get redirected to an error page that explains the problem, but of course the network can't do this over HTTPS (by design), so you instead just get an opaque protocol error. (The specifics of the error message actually lead me to suspect that they might just be shoving the HTTP error-page response into the HTTPS connection, never mind that it's the wrong protocol.)

It's possible that putting your site behind Cloudflare and enabling Encrypted Client Hello might fix this, though I haven't tested it.