Let's Debug

Test result for drone.lho.io using http-01

drone.lho.io has an AAAA (IPv6) record (2a01:4f8:1c1c:3602::) but a test request to this address over port 80 did not succeed. Your web server must have at least one working IPv4 or IPv6 address. You should either ensure that validation requests to this domain succeed over IPv6, or remove its AAAA record.
A timeout was experienced while communicating with drone.lho.io/2a01:4f8:1c1c:3602::: Get http://drone.lho.io/.well-known/acme-challenge/letsdebug-test: context deadline exceeded

Trace:
@0ms: Making a request to http://drone.lho.io/.well-known/acme-challenge/letsdebug-test (using initial IP 2a01:4f8:1c1c:3602::)
@0ms: Dialing 2a01:4f8:1c1c:3602::
@10000ms: Experienced error: context deadline exceeded
Debug
Requests made to the domain
Request to: drone.lho.io/2a01:4f8:1c1c:3602::, Result: [Address Type=IPv6,Server=,HTTP Status=0], Issue: AAAANotWorking
Trace:
@0ms: Making a request to http://drone.lho.io/.well-known/acme-challenge/letsdebug-test (using initial IP 2a01:4f8:1c1c:3602::)
@0ms: Dialing 2a01:4f8:1c1c:3602::
@10000ms: Experienced error: context deadline exceeded

Request to: drone.lho.io/159.69.29.156, Result: [Address Type=IPv4,Server=nginx/1.10.3,HTTP Status=301,Number of Redirects=1,Final HTTP Status=404], Issue:
Trace:
@0ms: Making a request to http://drone.lho.io/.well-known/acme-challenge/letsdebug-test (using initial IP 159.69.29.156)
@0ms: Dialing 159.69.29.156
@176ms: Server response: HTTP 301 Moved Permanently
@176ms: Received redirect to https://drone.lho.io/.well-known/acme-challenge/letsdebug-test
@176ms: Dialing 159.69.29.156
@530ms: Server response: HTTP 404 Not Found

Debug
A and AAAA records found for this domain
drone.lho.io. 0 IN A 159.69.29.156
drone.lho.io. 0 IN AAAA 2a01:4f8:1c1c:3602::
Challenge update failures for drone.lho.io in order https://acme-staging-v02.api.letsencrypt.org/acme/order/5751349/22131312
acme: error code 403 "urn:ietf:params:acme:error:unauthorized": Invalid response from http://drone.lho.io/.well-known/acme-challenge/B09iyLjLBS5ERiBWiG7JHDC-eRRa_2XSBwzwkN0JGIY: "<html>\r\n<head><title>404 Not Found</title></head>\r\n<body bgcolor=\"white\">\r\n<center><h1>404 Not Found</h1></center>\r\n<hr><center>"
Debug
The IANA public suffix is the TLD of the Registered Domain
The TLD for drone.lho.io is: io
Debug
2 Certificates contributing to rate limits for this domain

Serial: 296417126171812518680027332378581175978154
NotBefore: 2019-01-31 14:14:19 +0000 UTC
Names: [drone.lho.io]

Serial: 323301747880991811387608985558695017431275
NotBefore: 2019-01-27 15:40:52 +0000 UTC
Names: [drone.lho.io]

Debug
The current status.io status for Let's Encrypt
Operational

Submitted Jan 31 19:56:03 2019. Sat in queue for 4ms. Completed in 30s. Hide verbose information.