Origin Server

The origin server is your actual web server, the machine (physical or virtual) that hosts your website's files, runs your application code, and generates responses. When you use a CDN or reverse proxy like Cloudflare, visitors do not connect directly to the origin. Instead, Cloudflare sits in front and forwards requests to the origin on their behalf. Most Cloudflare 5xx errors (520-526) indicate a problem between Cloudflare and your origin server. The origin is sometimes called the "upstream" server.