Lets Encrypt request failed - IPv6 last letter missing


I´m trying to request a Lets Encrypt cert, but with no success. The server already hosts three domain with a Let Encrypt certificade, but this one I´m not getting it to work.

The answer is always ‘timeout’. Well, checking it, I realized that the IPv6 has a missing last letter. My IPv6 is [2600:xxxx::xxxx:xxxx:xxxx:304a] and the Lets Encrypt error is [2600:xxxx::xxxx:xxxx:xxxx:304].

Don´t know why. Don´t know why the others domains is working well (I think this is because I hold the DNS of the other domains, but this one not). But I´m not sure.

When I access the URL of the token, I can download it. So I don´t know why Lets Encrypt can´t.

Here is the output:

Parsing account key... Parsing CSR... Registering account... Already registered! Verifying fanfoto.phooto.com.br... Traceback (most recent call last): File "/usr/share/webmin/webmin/acme_tiny.py", line 235, in main(sys.argv[1:]) File "/usr/share/webmin/webmin/acme_tiny.py", line 231, in main signed_crt = get_crt(args.account_key, args.csr, args.acme_dir, args.dns_hook, args.cleanup_hook, log=LOGGER, CA=args.ca) File "/usr/share/webmin/webmin/acme_tiny.py", line 184, in get_crt domain, challenge_status)) ValueError: fanfoto.phooto.com.br challenge did not pass: {u'status': u'invalid', u'validationRecord': [{u'addressesResolved': [u'', u'2600:3c00::f03c:91ff:fe7a:304'], u'url': u'http://fanfoto.phooto.com.br/.well-known/acme-challenge/T_I24FPwrlcsN2N_Hu_lPmnDNR34ipgoAKpzL_GWj_E', u'hostname': u'fanfoto.phooto.com.br', u'addressesTried': [], u'addressUsed': u'2600:3c00::f03c:91ff:fe7a:304', u'port': u'80'}], u'keyAuthorization': u'T_I24FPwrlcsN2N_Hu_lPmnDNR34ipgoAKpzL_GWj_E.aJYgA8N_NBcTXd6ozzWs_Zicozkn0sO2p6Y6rfFLj7o', u'uri': u'https://acme-v01.api.letsencrypt.org/acme/challenge/LfkfpBzKHRucjCSli88TqTq3QBR7CZkq8_CYhe1hPvg/2345223326', u'token': u'T_I24FPwrlcsN2N_Hu_lPmnDNR34ipgoAKpzL_GWj_E', u'error': {u'status': 400, u'type': u'urn:acme:error:connection', u'detail': u'Fetching http://fanfoto.phooto.com.br/.well-known/acme-challenge/T_I24FPwrlcsN2N_Hu_lPmnDNR34ipgoAKpzL_GWj_E: Timeout'}, u'type': u'http-01'}