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"