Again challenge issue on nginx and duckdns

[gabbiano83]

Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. https://crt.sh/?q=example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.

My domain is:
seagull-home.duckdns.org

I ran this command:
certbot renew --dry-run

It produced this output:
....

---

Processing /etc/letsencrypt/renewal/seagull-home.duckdns.org.conf

---

Cert is due for renewal, auto-renewing...
Plugins selected: Authenticator nginx, Installer nginx
Renewing an existing certificate
Performing the following challenges:
http-01 challenge for seagull-home.duckdns.org
Waiting for verification...
Challenge failed for domain seagull-home.duckdns.org
http-01 challenge for seagull-home.duckdns.org
Cleaning up challenges
Attempting to renew cert (seagull-home.duckdns.org) from /etc/letsencrypt/renewal/seagull-home.duckdns.org.conf produced an unexpected error: Some challenges have failed.. Skipping.
All renewal attempts failed. The following certs could not be renewed:
/etc/letsencrypt/live/seagull-home.duckdns.org/fullchain.pem (failure)

---

** DRY RUN: simulating 'certbot renew' close to cert expiry
** (The test certificates below have not been saved.)

All renewal attempts failed. The following certs could not be renewed:
/etc/letsencrypt/live/seagull-home.duckdns.org/fullchain.pem (failure)
** DRY RUN: simulating 'certbot renew' close to cert expiry
** (The test certificates above have not been saved.)

---

1 renew failure(s), 0 parse failure(s)

IMPORTANT NOTES:

• The following errors were reported by the server:

  Domain: seagull-home.duckdns.org
  Type: connection
  Detail: Fetching
  http://seagull-home.duckdns.org/.well-known/acme-challenge/HCCGRxgTWKMSPqWbtydTKmGLWiQrDq_tiwc6BEa_cPg:
  Error getting validation data

  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.

My web server is (include version):
nginx
The operating system my web server runs on is (include version):
Ubuntu 18.04.5

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):
no

The version of my client is (e.g. output of certbot --version or certbot-auto --version if you're using Certbot):
certbot 1.9.0

I'm unable to renew, since challenge file always change, how could I configure nginx to always respond with http 200 ? Currently respond as 404 not found

[Osiris]

There seems to be some issue with the current IP address (82.56.24.58) when connecting to port 80:

It responds with a "No route to host" error:

osiris@server ~ $ telnet seagull-home.duckdns.org 80
Trying 82.56.24.58...
telnet: connect to address 82.56.24.58: No route to host

root@server ~ # traceroute -T -p 80 seagull-home.duckdns.org
(...)
15  host-82-56-24-58.retail.telecomitalia.it (82.56.24.58)  34.037
ms !X  36.944 ms !X  34.436 ms !X

All this while port 443 works nicely.

Your firewall is probably blocking port 80.