The domain www.flystore.net 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-
Some DNS records were found that indicate TXT records may have been incorrectly manually entered into DNS editor interfaces. The correct way to enter these records is to either remove the domain from the label (so enter "_acme-challenge.www.example.org" as "_acme-challenge.www") or include a period (.) at the end of the label (enter "_acme-challenge.example.org.").
The following probably-erroneous TXT records were found:
_acme-challenge.www.flystore.net.flystore.net. 0 IN TXT "mt-60634731"
Challenge update failures for www.flystore.net in order https://acme-staging-v02.api.letsencrypt.org/acme/order/5751349/4462262544
acme: error code 400 "urn:ietf:params:acme:error:dns": DNS problem: NXDOMAIN looking up TXT for _acme-challenge.www.flystore.net - check that a DNS record exists for this domain
The IANA public suffix is the TLD of the Registered Domain
The TLD for www.flystore.net is: net
The current status.io status for Let's Encrypt
Operational