My domain has a valid and activated "Let's Encrypt!" certificate, and going to
https://example.com works as it should and shows as being secure in the browser.
Through Plesk Onyx 17.5.3 I have activated the option Permanent SEO-safe 301 redirect from HTTP to HTTPS in Hosting Settings.
But when going to
http://example.com, it shows a 403.4 Forbidden error and that I should use the https version of the website instead of redirecting to it.