The domain gigantic.io is being served through Cloudflare CDN. Any Let's Encrypt certificate installed on the origin server will only encrypt traffic between the server and Cloudflare. It is strongly recommended that the SSL option 'Full SSL (strict)' be enabled.
https://support.cloudflare.com/hc/en-us/articles/200170416-What-do-the-SSL-options-mean-
gigantic.io is currently affected by Let's Encrypt-based rate limits (https://letsencrypt.org/docs/rate-limits/). You may review certificates that have already been issued by visiting https://crt.sh/?q=%gigantic.io . Please note that it is not possible to ask for a rate limit to be manually cleared.
The 'Certificates per Registered Domain' limit (20 certificates per week that share the same Registered Domain: gigantic.io) has been exceeded. There is no way to work around this rate limit. The next non-renewal certificate for this Registered Domain should be issuable after 2018-05-19 18:59:53 +0000 UTC (36h42m0s from now).