Invalid response acme challenge - same IP as subdomain

Hi there,

I have an issue creating my ssl certicate for my main domain. The A-Entry in my DNS settings lead to the same IP of both, subdomain and main one.

Now strangely I could create the certificate for the subdomain, but not for the main one. I get following error:

Type: unauthorized
Detail: Invalid response from
“\r\n404 Not Found\r\n<body

404 Not


I have no idea where the problem could be.

Thanks for your help!

My domain is: (subdomain:

I ran this command: certbot

It produced this output:

My web server is (include version): Apache/2.4.29 (Ubuntu)

The operating system my web server runs on is (include version): Ubuntu 18.04

My hosting provider, if applicable, is: netcup

I can login to a root shell on my machine (yes or no, or I don’t know): yes

I’m using a control panel to manage my site (no, or provide the name and version of the control panel): yes

They don’t have exactly the same IPs:         (insecure)  86400  A         (insecure)  86400  AAAA  2a03:4000:30:3633::11:3954  (insecure)  86400  A

Are you sure the IPv6 address is correct?


The IPv6 address is running an Nginx web server, so it’s pointed to a different server, or set up differently.

Oh, I only checked the A record. Should I just delete the AAAA record or what would you recommend? To be honest I’m not sure if or how important it is to have the IPV6 IP as well.

It’s good to support IPv6, but the most important thing is for your DNS records to be correct.

Is that your IPv6 address?

It does have a valid certificate for It has a web page saying “Hier entsteht eine neue Webseite.”

Are you using both Apache and Nginx?

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