Sudden renewal failure: The Certificate Authority failed to download the challenge files from the temporary standalone webserver started by Certbot on port 80

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3

Got it - I have no idea where I picked that up from. My renewal procedure is saved in org-Roam, so I use the same commands each time.

Result of that is:

$ sudo certbot renew --dry-run
Saving debug log to /var/log/letsencrypt/letsencrypt.log

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Processing /etc/letsencrypt/renewal/13qw.duckdns.org.conf
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Account registered.
Simulating renewal of an existing certificate for 13qw.duckdns.org

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Congratulations, all simulated renewals succeeded: 
  /etc/letsencrypt/live/13qw.duckdns.org/fullchain.pem (success)
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