Cheap Web Space, Domain Name:
Web Space With E-Mail, PHP/MySQL.

Symptom

You have assigned an external (non-Bitpalace managed domain) to your webspace and are trying to create or extend a Let's Encrypt SSL certificate. After a few seconds, the server displays an error message:

Invalid response from https://acme-v01.api.letsencrypt.org/acme/authz/sabc3z2WKoUsD_3JYzAWUGMCXUSYhoZuSTsV-IHmbPFc.
Details:
Type: urn:acme:error:connection
Status: 400
Detail: Fetching https:///.well-known/acme-challenge/tuZbABO_nBLLHIYH3rPzG5WgKNAWaGKbWuU67yqqwX4: Timeout during connect (likely firewall problem)

Cause

You have entered an IPv6 route (an AAAA record) in your name server for the domain. If an IPv6 route exists, Let's Encrypt reads only the IPv6 address and tries to connect to the server using IPv6. If this route fails, Let's Encrypt will not attempt to use the additional IPv4 route, but will terminate with error 400 and a timeout message

The reason for the inaccessibility of the webspace account via IPv6 is a security shutdown of one of our security software packages. As soon as necessary updates from third-party providers of this software become available, all webspace accounts will also be reachable again on IPv6 addresses. At the moment you should rely solely on IPv4. Domain names rented from Bitpalace are configured correctly by default. IPv6 does not yield any advantages over IPv4 for your webspace account. In practice, it therefore does not harm any aspect of your web space operations to make the domain available via IPv4.

Solution

Remove the IPv6 address (the AAAA record) from your DNS configuration. Use only IPv4. Wait approximately 4 to 24 hours for the changed configuration to be propagated throughout the Internet. Afterwards, retry creating or renewing the SSL certificate.

Overview of frequently asked questions