523: Origin is unreachable

Is your origin's DNS record / IP address definitely correct and pointing at a live server?

Yes, DNS/IP looks correct

Cloudflare cannot reach your origin at the network level, even though the DNS/IP configuration looks correct.

Check

Confirm your origin's firewall/security group allows inbound traffic from Cloudflare's published IP ranges on the relevant port.

Fix

Add or correct the firewall rule allowing Cloudflare's IP ranges.

curl https://www.cloudflare.com/ips-v4
curl https://www.cloudflare.com/ips-v6

Verify

Retry the request through Cloudflare and confirm it now reaches your origin.

Not sure / might be wrong

Your DNS record in Cloudflare may be pointing at an IP address that no longer has a live server behind it.

Check

In the Cloudflare DNS dashboard, confirm the A/AAAA record for this hostname points at your current, live origin IP.

Fix

Update the DNS record to the correct origin IP address.

Verify

Wait for DNS propagation, then retry the request through Cloudflare.

Want to narrow it down interactively instead? Use the error lookup tool.