www.kleos.ai has an AAAA (IPv6) record (2a01:7e01::f03c:91ff:fe08:e041) but a test request to this address over port 80 did not succeed. Let's Encrypt will prefer to use AAAA records, if present, and will not fall back to IPv4 records. You should either ensure that validation requests to this domain succeed over IPv6, or remove its AAAA record.
Get https://www.kleos.ai/.well-known/acme-challenge/letsdebug-test: EOF
Trace:
@0ms: Making a request to http://www.kleos.ai/.well-known/acme-challenge/letsdebug-test (using initial IP 2a01:7e01::f03c:91ff:fe08:e041)
@0ms: Dialing 2a01:7e01::f03c:91ff:fe08:e041
@171ms: Server response: HTTP 301 Moved Permanently
@171ms: Received redirect to https://www.kleos.ai/.well-known/acme-challenge/letsdebug-test
@171ms: Dialing 2a01:7e01::f03c:91ff:fe08:e041
@342ms: Experienced error: EOF
A test authorization for www.kleos.ai to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
Fetching https://www.kleos.ai/.well-known/acme-challenge/gFa30McHGorMFtbFd7BupCo9PlUEy6hYhh2RgVkfUK8: Connection reset by peer