Let's Debug

Test result for jancsi.cz using http-01

jancsi.cz has an AAAA (IPv6) record (2a03:3b40:101:93::1) but a test request to this address over port 80 did not succeed. Your web server must have at least one working IPv4 or IPv6 address. You should either ensure that validation requests to this domain succeed over IPv6, or remove its AAAA record.
Get "http://jancsi.cz/.well-known/acme-challenge/letsdebug-test": dial tcp [2a03:3b40:101:93::1]:80: connect: connection refused

Trace:
@0ms: Making a request to http://jancsi.cz/.well-known/acme-challenge/letsdebug-test (using initial IP 2a03:3b40:101:93::1)
@0ms: Dialing 2a03:3b40:101:93::1
@95ms: Experienced error: dial tcp [2a03:3b40:101:93::1]:80: connect: connection refused
A test authorization for jancsi.cz to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
185.8.166.34: Fetching https://jancsi.cz/.well-known/acme-challenge/mCqwsHQXteJLxtjLkv4kmrIuo-aKBr83Ar_J5yvgmCQ: Connection refused

Submitted Jan 29 21:30:57 2023. Sat in queue for 6ms. Completed in 5s. Show verbose information.