Certbot standalone port 80 issue

Hi :slight_smile:
Certbot unable to renew cert because to connection to my IP not good. I do not run any service on port 80. Just for checking I installed nginx (and created an index.html) and got an answer (I uninstalled nginx again and no response on port 80). Trying to get new cert via certbot:
certbot certonly --standalone -v -d yy.xxx.zz
same error, no response on port 80.
Timeout during connect (likely firewall problem)
OK, then I installed another HTTP server, lightttp, created index.html file and got again the website via port 80. I uninstalled it again, restartet the server. Tried certbot again: some challanges failed.
What am I doing so wrong?

Edit 1: Is there any way to know Let's Ecrypt's IP addresses?

When you opened this thread in the Help section, you should have been provided with a questionnaire. Maybe you didn't get it somehow (which is weird), or you've decided to delete it. In any case, all the answers to this questionnaire are required:

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