Hi there,
Digging around in our logs, this was what I was able to find out.
Over the last 7 days, there have been 60 logged errors on your zone dddcodigo.com.br and of those 30 are 521 status codes.
context: Fail to connect to (origin IP address) cause: Connection refused (os error 111), status: 521
Having said this I would make sure:
1 - The port you’re trying to reach is open at your origin
2 - Cloudflare IP addresses are allowed at your origin without any kind of mitigation.
3 - Cross-reference you origin logs at the time of the errors to search for anomalies.
Take care.