Fix Cloudflare Proxy Pass

I have a Node.js app running on port 3000. I’m met with a browser error complaining about an “invalid SSL certificate on origin”. I have a proxy pass for my sub domain setup on cloud fare under origin rules. I do not want to use nginx on server.

The server itself has a Certbot-generated Let’s Encrypt certificate installed and working when I point the browser straight to the IP, so the problem seems to live in the hand-off between Cloudflare and the origin. I tried wiring things up through Origin Rules inside the Page Rules area, hoping to avoid installing or configuring Nginx, yet the proxy pass still fails.

Here’s what I need from you:

• Audit the current DNS, SSL/TLS and Origin Rule settings in my Cloudflare dashboard, then adjust them so https://mp3.eternityready.com flows cleanly to the Node process on port 3000.
• Eliminate the certificate warning without adding any extra reverse proxy layer. If keeping the existing Certbot cert is viable, great—otherwise please guide me to whatever certificate arrangement Cloudflare expects.
• Leave me with a concise summary of every change so I can reproduce the setup on staging later.

I can grant temporary server and dashboard access (Ubuntu, Node 18). The job is done when the site loads over HTTPS, the orange cloud stays on, and standard SSL checkers report no errors.