I tried to open port and even disable firewall.
I have to use IPv6.
I ran this command:
sudo certbot certonly --standalone
It produced this output:
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Please enter the domain name(s) you would like on your certificate (comma and/or
space separated) (Enter 'c' to cancel): files.soxd.hu
Requesting a certificate for files.soxd.hu
Certbot failed to authenticate some domains (authenticator: standalone). The Certificate Authority reported these problems:
Detail: 2a02:ab88:7200:d600:f42f:320e:56de:ced7: Fetching http://files.soxd.hu/.well-known/acme-challenge/30uPiBsQL4VI8K6LFW2tC6pEzxTzyf9CbStpmk6wULU: Timeout during connect (likely firewall problem)
This will show you a URL and then ask to press enter. Do NOT press enter. Just leave it paused like that and let us know when it is ready. Or, while it is paused try to reach your domain using http://files.soxd.hu from outside your local network. Like using a mobile phone with wifi disabled to use the carrier's network.
You should be able to get some response from Certbot using --debug-challenges while it is paused.
If you get a timeout you will need to inspect each part of your local network to see where it may be blocked. And, contact your ISP about port 80.