title: LetsEncrypt Challenge failed for domain
body: <p>Running this with my domain:</p>
  <pre><code>sudo certbot certonly --standalone --preferred-challenges http --server https://acme-staging-v02.api.letsencrypt.org/directory --register-unsafely-without-email -d example.com
  
  Saving debug log to /var/log/letsencrypt/letsencrypt.log
  Plugins selected: Authenticator standalone, Installer None
  Obtaining a new certificate
  Performing the following challenges:
  http-01 challenge for example.com
  Waiting for verification...
  Challenge failed for domain example.com
  http-01 challenge for example.com
  Cleaning up challenges
  Some challenges have failed.
  
  IMPORTANT NOTES:
   - The following errors were reported by the server:
  
     Domain: exxample.com
     Type:   connection
     Detail: correct.ip.address: Fetching
     http://example.com/.well-known/acme-challenge/jHPVDWvcICxX0vt7auklR1vR8osXbSOEqbidqE7JmcE:
     Timeout during connect (likely firewall problem)
  
     To fix these errors, please make sure that your domain name was
     entered correctly and the DNS A/AAAA record(s) for that domain
     contain(s) the right IP address. Additionally, please check that
     your computer has a publicly routable IP address and that no
     firewalls are preventing the server from communicating with the
     client. If you're using the webroot plugin, you should also verify
     that you are serving files from the webroot path you provided.
  </code></pre>
  <p>Note: Without using <code>--standalone</code> I am able to download the file <code>wget http://example.com/.well-known/acme-challenge/8SPcqxypfvqpVz-koSWJxesGw4HuSOD84J6k5xnFPZ0</code></p>
  <p>I have port forward working correct and in the Ubuntu server I did <code>ufw 80</code> and <code>ufw 443</code>. But still note, that I am able to wget the file manually.</p>
  <p>I have ipv4 records, but no AAAA ipv6 records - but I guess it should work with ipv4.</p>
  <p>And I have no problem serving <code>pyton3 -m http.server 80</code> and curl to the server.</p>
  <p>Am I missing something?</p>