Title and output say it all, web seems to be accessible anywhere from Czech Rep.
Command: sudo certbot renew (ver: 0.19.0-1, updated from buster rep.)
Webserver: nginx/1.10.3, no wordpress
OS: Linux 4.9.0-4-armmp-lpae #1 SMP Debian (Stretch) 4.9.51-1 (2017-09-28) armv7l GNU/Linux
Output: Processing /etc/letsencrypt/renewal/rict.cz.conf
Cert is due for renewal, auto-renewing... Plugins selected: Authenticator webroot, Installer None Attempting to renew cert (rict.cz) from /etc/letsencrypt/renewal/rict.cz.conf produced an unexpected error: HTTPSConnectionPool(host='acme-v01.api.letsencrypt.org', port=443): Max retries exceeded with url: /directory (Caused by ConnectTimeoutError(<requests.packages.urllib3.connection.VerifiedHTTPSConnection object at 0xb6ac34f0>, 'Connection to acme-v01.api.letsencrypt.org timed out. (connect timeout=45)')). Skipping. All renewal attempts failed. The following certs could not be renewed: /etc/letsencrypt/live/rict.cz/fullchain.pem (failure)