Just restarted caddy service, here is a more detailed logs.
TLDR: Maybe the revelant log is:
Jan 31 20:56:21 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730981.027879,"logger":"tls.obtain","msg":"could not get certificate from issuer","identifier":"cockpit.pavo.pw","issuer":"acme-v02.api.letsencrypt.org-directory","error":"HTTP 400 urn:ietf:params:acme:error:malformed - Unable to contact \"cockpit.pavo.pw\" at \"2a00:6d42:1242:1c00::5f\", no IPv4 addresses to try as fallback"}
Full logs:
Jan 31 20:46:08 eu-it.pavo.pw systemd[1]: Started Caddy.
Jan 31 20:46:08 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730368.3330045,"msg":"serving initial configuration"}
Jan 31 20:46:08 eu-it.pavo.pw caddy[37904]: {"level":"warn","ts":1706730368.336733,"logger":"tls","msg":"storage cleaning happened too recently; skipping for now","storage":"FileStorage:/var/lib/caddy/.local/share/caddy","instance":"398ef0d5-3f64-4b2f-9295-46cbf1aefec7","try_again":1706816768.3367307,"try_again_in":86399.999999094}
Jan 31 20:46:08 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730368.3370643,"logger":"tls","msg":"finished cleaning storage units"}
Jan 31 20:46:08 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730368.3373895,"logger":"tls.cache.maintenance","msg":"started background certificate maintenance","cache":"0xc00027bb80"}
Jan 31 20:46:08 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730368.3386922,"logger":"tls.obtain","msg":"acquiring lock","identifier":"cockpit.pavo.pw"}
Jan 31 20:46:08 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730368.3405008,"logger":"tls.obtain","msg":"lock acquired","identifier":"cockpit.pavo.pw"}
Jan 31 20:46:08 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730368.340875,"logger":"tls.obtain","msg":"obtaining certificate","identifier":"cockpit.pavo.pw"}
Jan 31 20:46:08 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730368.343171,"logger":"http","msg":"waiting on internal rate limiter","identifiers":["cockpit.pavo.pw"],"ca":"https://acme-v02.api.letsencrypt.org/directory","account":""}
Jan 31 20:46:08 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730368.3432972,"logger":"http","msg":"done waiting on internal rate limiter","identifiers":["cockpit.pavo.pw"],"ca":"https://acme-v02.api.letsencrypt.org/directory","account":""}
Jan 31 20:46:09 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730369.5571034,"logger":"http.acme_client","msg":"trying to solve challenge","identifier":"cockpit.pavo.pw","challenge_type":"http-01","ca":"https://acme-v02.api.letsencrypt.org/directory"}
Jan 31 20:46:10 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730370.1305127,"logger":"http.acme_client","msg":"challenge failed","identifier":"cockpit.pavo.pw","challenge_type":"http-01","problem":{"type":"urn:ietf:params:acme:error:connection","title":"","detail":"2a00:6d42:1242:1c00::5f: Fetching http://cockpit.pavo.pw/.well-known/acme-challenge/K8FFQnkEf-XzJpIGKd_6luJsioSYExq4APMf72RjOXY: Error getting validation data","instance":"","subproblems":[]}}
Jan 31 20:46:10 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730370.1309326,"logger":"http.acme_client","msg":"validating authorization","identifier":"cockpit.pavo.pw","problem":{"type":"urn:ietf:params:acme:error:connection","title":"","detail":"2a00:6d42:1242:1c00::5f: Fetching http://cockpit.pavo.pw/.well-known/acme-challenge/K8FFQnkEf-XzJpIGKd_6luJsioSYExq4APMf72RjOXY: Error getting validation data","instance":"","subproblems":[]},"order":"https://acme-v02.api.letsencrypt.org/acme/order/1377580036/240850078807","attempt":1,"max_attempts":3}
Jan 31 20:46:11 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730371.6191645,"logger":"http.acme_client","msg":"trying to solve challenge","identifier":"cockpit.pavo.pw","challenge_type":"tls-alpn-01","ca":"https://acme-v02.api.letsencrypt.org/directory"}
Jan 31 20:46:12 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730372.1790886,"logger":"http.acme_client","msg":"challenge failed","identifier":"cockpit.pavo.pw","challenge_type":"tls-alpn-01","problem":{"type":"urn:ietf:params:acme:error:malformed","title":"","detail":"Unable to contact \"cockpit.pavo.pw\" at \"2a00:6d42:1242:1c00::5f\", no IPv4 addresses to try as fallback","instance":"","subproblems":[]}}
Jan 31 20:46:12 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730372.179562,"logger":"http.acme_client","msg":"validating authorization","identifier":"cockpit.pavo.pw","problem":{"type":"urn:ietf:params:acme:error:malformed","title":"","detail":"Unable to contact \"cockpit.pavo.pw\" at \"2a00:6d42:1242:1c00::5f\", no IPv4 addresses to try as fallback","instance":"","subproblems":[]},"order":"https://acme-v02.api.letsencrypt.org/acme/order/1377580036/240850083897","attempt":2,"max_attempts":3}
Jan 31 20:46:12 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730372.1798322,"logger":"tls.obtain","msg":"could not get certificate from issuer","identifier":"cockpit.pavo.pw","issuer":"acme-v02.api.letsencrypt.org-directory","error":"HTTP 400 urn:ietf:params:acme:error:malformed - Unable to contact \"cockpit.pavo.pw\" at \"2a00:6d42:1242:1c00::5f\", no IPv4 addresses to try as fallback"}
Jan 31 20:46:12 eu-it.pavo.pw caddy[37904]: {"level":"warn","ts":1706730372.1806428,"logger":"http","msg":"missing email address for ZeroSSL; it is strongly recommended to set one for next time"}
Jan 31 20:46:12 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730372.2244542,"logger":"tls.obtain","msg":"could not get certificate from issuer","identifier":"cockpit.pavo.pw","issuer":"acme.zerossl.com-v2-DV90","error":"account pre-registration callback: performing EAB credentials request: Post \"https://api.zerossl.com/acme/eab-credentials-email\": dial tcp 34.196.131.225:443: connect: network is unreachable"}
Jan 31 20:46:12 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730372.2248123,"logger":"tls.obtain","msg":"will retry","error":"[cockpit.pavo.pw] Obtain: account pre-registration callback: performing EAB credentials request: Post \"https://api.zerossl.com/acme/eab-credentials-email\": dial tcp 34.196.131.225:443: connect: network is unreachable","attempt":1,"retrying_in":60,"elapsed":3.884139548,"max_duration":2592000}
Jan 31 20:47:12 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730432.226078,"logger":"tls.obtain","msg":"obtaining certificate","identifier":"cockpit.pavo.pw"}
Jan 31 20:47:13 eu-it.pavo.pw caddy[37904]: {"level":"info","ts":1706730433.3537796,"logger":"http.acme_client","msg":"trying to solve challenge","identifier":"cockpit.pavo.pw","challenge_type":"tls-alpn-01","ca":"https://acme-staging-v02.api.letsencrypt.org/directory"}
Jan 31 20:47:13 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730433.9573002,"logger":"http.acme_client","msg":"challenge failed","identifier":"cockpit.pavo.pw","challenge_type":"tls-alpn-01","problem":{"type":"urn:ietf:params:acme:error:malformed","title":"","detail":"Unable to contact \"cockpit.pavo.pw\" at \"2a00:6d42:1242:1c00::5f\", no IPv4 addresses to try as fallback","instance":"","subproblems":[]}}
Jan 31 20:47:13 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730433.9577062,"logger":"http.acme_client","msg":"validating authorization","identifier":"cockpit.pavo.pw","problem":{"type":"urn:ietf:params:acme:error:malformed","title":"","detail":"Unable to contact \"cockpit.pavo.pw\" at \"2a00:6d42:1242:1c00::5f\", no IPv4 addresses to try as fallback","instance":"","subproblems":[]},"order":"https://acme-staging-v02.api.letsencrypt.org/acme/order/122997564/14090202514","attempt":1,"max_attempts":3}
Jan 31 20:47:13 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730433.95798,"logger":"tls.obtain","msg":"could not get certificate from issuer","identifier":"cockpit.pavo.pw","issuer":"acme-v02.api.letsencrypt.org-directory","error":"HTTP 400 urn:ietf:params:acme:error:malformed - Unable to contact \"cockpit.pavo.pw\" at \"2a00:6d42:1242:1c00::5f\", no IPv4 addresses to try as fallback"}
Jan 31 20:47:13 eu-it.pavo.pw caddy[37904]: {"level":"warn","ts":1706730433.9584997,"logger":"http","msg":"missing email address for ZeroSSL; it is strongly recommended to set one for next time"}
Jan 31 20:47:13 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730433.9807427,"logger":"tls.obtain","msg":"could not get certificate from issuer","identifier":"cockpit.pavo.pw","issuer":"acme.zerossl.com-v2-DV90","error":"account pre-registration callback: performing EAB credentials request: Post \"https://api.zerossl.com/acme/eab-credentials-email\": dial tcp 34.237.95.29:443: connect: network is unreachable"}
Jan 31 20:47:13 eu-it.pavo.pw caddy[37904]: {"level":"error","ts":1706730433.9810572,"logger":"tls.obtain","msg":"will retry","error":"[cockpit.pavo.pw] Obtain: account pre-registration callback: performing EAB credentials request: Post \"https://api.zerossl.com/acme/eab-credentials-email\": dial tcp 34.237.95.29:443: connect: network is unreachable","attempt":2,"retrying_in":120,"elapsed":65.640384345,"max_duration":2592000}