Welcome to the Cloudflare Community. 
Even on the most expensive plans Cloudflare is very much a self-service platform. This means that while the Community can help you find the right direction, you will need to take the action required to achieve your desired results.
Cloudflare is not likely hosting your website. Cloudflare is a security and performance platform that operates between your website and your vistors. If you click the 521 in your post or here in my reply, you will be taken to a Community Tutorial that lists items to check. The problem you describe is likely with the webserver that hosts your site. You will need to find out who that is. The party that set it up wild be the best place to start.