The domain cdst3str.xyz is being served through Cloudflare CDN. Any Let's Encrypt certificate installed on the origin server will only encrypt traffic between the server and Cloudflare. It is strongly recommended that the SSL option 'Full SSL (strict)' be enabled.
https://support.cloudflare.com/hc/en-us/articles/200170416-What-do-the-SSL-options-mean-
Requests made to the domain
Request to: cdst3str.xyz/2606:4700:3030::6812:224e, Result: [Address=2606:4700:3030::6812:224e,Address Type=IPv6,Server=cloudflare,HTTP Status=302,Number of Redirects=1,Final HTTP Status=404], Issue:
Trace:
@0ms: Making a request to http://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test (using initial IP 2606:4700:3030::6812:224e)
@0ms: Dialing 2606:4700:3030::6812:224e
@210ms: Server response: HTTP 302 Moved Temporarily
@210ms: Received redirect to https://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test
@211ms: Dialing 2606:4700:3030::6812:224e
@1535ms: Server response: HTTP 404 Not Found
Request to: cdst3str.xyz/2606:4700:3035::6812:234e, Result: [Address=2606:4700:3035::6812:234e,Address Type=IPv6,Server=cloudflare,HTTP Status=302,Number of Redirects=1,Final HTTP Status=404], Issue:
Trace:
@0ms: Making a request to http://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test (using initial IP 2606:4700:3035::6812:234e)
@0ms: Dialing 2606:4700:3035::6812:234e
@275ms: Server response: HTTP 302 Moved Temporarily
@275ms: Received redirect to https://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test
@276ms: Dialing 2606:4700:3035::6812:234e
@1115ms: Server response: HTTP 404 Not Found
Request to: cdst3str.xyz/2606:4700:3036::ac43:8ed4, Result: [Address=2606:4700:3036::ac43:8ed4,Address Type=IPv6,Server=cloudflare,HTTP Status=302,Number of Redirects=1,Final HTTP Status=404], Issue:
Trace:
@0ms: Making a request to http://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test (using initial IP 2606:4700:3036::ac43:8ed4)
@0ms: Dialing 2606:4700:3036::ac43:8ed4
@206ms: Server response: HTTP 302 Moved Temporarily
@206ms: Received redirect to https://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test
@206ms: Dialing 2606:4700:3036::ac43:8ed4
@521ms: Server response: HTTP 404 Not Found
Request to: cdst3str.xyz/104.18.35.78, Result: [Address=104.18.35.78,Address Type=IPv4,Server=cloudflare,HTTP Status=302,Number of Redirects=1,Final HTTP Status=404], Issue:
Trace:
@0ms: Making a request to http://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test (using initial IP 104.18.35.78)
@0ms: Dialing 104.18.35.78
@201ms: Server response: HTTP 302 Moved Temporarily
@201ms: Received redirect to https://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test
@201ms: Dialing 104.18.35.78
@889ms: Server response: HTTP 404 Not Found
Request to: cdst3str.xyz/172.67.142.212, Result: [Address=172.67.142.212,Address Type=IPv4,Server=cloudflare,HTTP Status=302,Number of Redirects=1,Final HTTP Status=404], Issue:
Trace:
@0ms: Making a request to http://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test (using initial IP 172.67.142.212)
@0ms: Dialing 172.67.142.212
@204ms: Server response: HTTP 302 Moved Temporarily
@204ms: Received redirect to https://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test
@204ms: Dialing 172.67.142.212
@582ms: Server response: HTTP 404 Not Found
Request to: cdst3str.xyz/104.18.34.78, Result: [Address=104.18.34.78,Address Type=IPv4,Server=cloudflare,HTTP Status=302,Number of Redirects=1,Final HTTP Status=404], Issue:
Trace:
@0ms: Making a request to http://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test (using initial IP 104.18.34.78)
@0ms: Dialing 104.18.34.78
@212ms: Server response: HTTP 302 Moved Temporarily
@212ms: Received redirect to https://cdst3str.xyz/.well-known/acme-challenge/letsdebug-test
@212ms: Dialing 104.18.34.78
@1132ms: Server response: HTTP 404 Not Found
A and AAAA records found for this domain
cdst3str.xyz. 0 IN A 104.18.35.78
cdst3str.xyz. 0 IN A 172.67.142.212
cdst3str.xyz. 0 IN A 104.18.34.78
cdst3str.xyz. 0 IN AAAA 2606:4700:3030::6812:224e
cdst3str.xyz. 0 IN AAAA 2606:4700:3035::6812:234e
cdst3str.xyz. 0 IN AAAA 2606:4700:3036::ac43:8ed4
Challenge update failures for cdst3str.xyz in order https://acme-staging-v02.api.letsencrypt.org/acme/order/5751349/194337924
acme: error code 403 "urn:ietf:params:acme:error:unauthorized": Invalid response from https://cdst3str.xyz/.well-known/acme-challenge/nGl1CIMfsgDElWHNNpV9EYD70GZuCjjF3PeRfJrRpyc [2606:4700:3035::6812:234e]: "<html>\r\n<head><title>404 Not Found</title></head>\r\n<body>\r\n<center><h1>404 Not Found</h1></center>\r\n<hr><center>nginx</center>\r\n"