Within minutes of transferring to Cloudflare nameservers, I was alerted that my sites were down. I checked and get a message from Cloudflare that there is a host error, that the web server is not returning a connection. Checking the Cloudflare diagnostic center shows me several errors, including DNSSEC and others. The one that seems to me to be the key error is this:
HTTPS Status is “No, your request failed with a response status of 400 or above.”
I assume it just means the site appears down.
If I use a remote machine with a hosts file (circumventing Cloudflare), the sites are up.
I use a firewall plenty of people use. I can’t think of a reason it would block client traffic from Cloudflare. Google searches don’t show others having this issue.
Right now, the sites are hosted at a residence. Searches for the ISP possibly blocking Cloudflare client traffic don’t show anything.
This may be the most likely cause. You’d have to open a ticket and ask Support to test their connection to your IP address.
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