Problem with SSL :S

[fritex]

Regarding your issue about 521 error:
https://support.cloudflare.com/hc/en-us/articles/115003011431-Troubleshooting-Cloudflare-5XX-errors#521error

Have you had an HTTPS connection at your host/origin before adding your domain to Cloudflare?
Moreover, to use Full SSL, you would need to have an SSL certificate at your host/origin.

Kindly, could you please try to follow the steps from the article below to solve your problem:

Community Tip - Fixing Error 521: Web server is down

Error Try the suggestions in this Community Tip to help you fix Error 521: Web server is down. Background A 521 error happens when we are unable to make a TCP connection to your origin server. Specifically, Cloudflare tried to connect to your origin server on port 80 or 443, but received a connection refused error. This is often caused by security or firewall software and happens if the origin server has directly refused Cloudflare’s proxy request. [Banner in tip catalog] Quick Fix Ideas …