Let's Debug

Test result for the-independent-friend.de using http-01

the-independent-friend.de has both AAAA (IPv6) and A (IPv4) records. While they both appear to be accessible on the network, we have detected that they produce differing results when sent an ACME HTTP validation request. This may indicate that the IPv4 and IPv6 addresses may unintentionally point to different servers, which would cause validation to fail.
[Address Type=IPv4,Response Code=404,Server=nginx/1.12.2] vs [Address Type=IPv6,Response Code=404,Server=Apache]
Debug
Requests made to the domain
Request to: the-independent-friend.de/2a01:488:42:1000:50ed:8499:db:fa85, Result: [Address Type=IPv6,Response Code=404,Server=Apache], Issue:
Request to: the-independent-friend.de/92.51.165.102, Result: [Address Type=IPv4,Response Code=404,Server=nginx/1.12.2], Issue:
Debug
A and AAAA records found for this domain
the-independent-friend.de. 0 IN A 92.51.165.102
the-independent-friend.de. 0 IN AAAA 2a01:488:42:1000:50ed:8499:db:fa85
Challenge update failures for the-independent-friend.de in order https://acme-staging-v02.api.letsencrypt.org/acme/order/5751349/1002339
acme: error code 403 "urn:ietf:params:acme:error:unauthorized": Invalid response from http://the-independent-friend.de/.well-known/acme-challenge/wdnbnefBoMCBkNW4asJoT6dB1n6hNgRkv-PHPjTlsNY: "<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<m"
Debug
The IANA public suffix is the TLD of the Registered Domain
The TLD for the-independent-friend.de is: de
Debug
The current status.io status for Let's Encrypt
Operational

Submitted May 16 13:49:01 2018. Sat in queue for 4ms. Completed in 2s. Hide verbose information.