Ensure that
- there is no typo in your IP address
- your host is accepting connections in Port 443
- Cloudflare IPs are allowlisted
- that there’s no rate limit.
Would you mind telling us the domain? We don’t have access to your account.
For reference
Please follow the steps in this post to solve your Problem:
The following ports are proxied by Cloudflare:
https://support.cloudflare.com/hc/en-us/articles/200169156-Which-ports-will-Cloudflare-work-with-