The domain pass.zaonpt.com 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-
Requests made to the domain
Request to: pass.zaonpt.com/2606:4700:3033::ac43:c63e, Result: [Address=2606:4700:3033::ac43:c63e,Address Type=IPv6,Server=cloudflare,HTTP Status=403], Issue:
Trace:
@0ms: Making a request to http://pass.zaonpt.com/.well-known/acme-challenge/letsdebug-test (using initial IP 2606:4700:3033::ac43:c63e)
@0ms: Dialing 2606:4700:3033::ac43:c63e
@127ms: Server response: HTTP 403 Forbidden
Request to: pass.zaonpt.com/2606:4700:3031::6815:2232, Result: [Address=2606:4700:3031::6815:2232,Address Type=IPv6,Server=cloudflare,HTTP Status=403], Issue:
Trace:
@0ms: Making a request to http://pass.zaonpt.com/.well-known/acme-challenge/letsdebug-test (using initial IP 2606:4700:3031::6815:2232)
@0ms: Dialing 2606:4700:3031::6815:2232
@16ms: Server response: HTTP 403 Forbidden
Request to: pass.zaonpt.com/104.21.34.50, Result: [Address=104.21.34.50,Address Type=IPv4,Server=cloudflare,HTTP Status=403], Issue:
Trace:
@0ms: Making a request to http://pass.zaonpt.com/.well-known/acme-challenge/letsdebug-test (using initial IP 104.21.34.50)
@0ms: Dialing 104.21.34.50
@20ms: Server response: HTTP 403 Forbidden
Request to: pass.zaonpt.com/172.67.198.62, Result: [Address=172.67.198.62,Address Type=IPv4,Server=cloudflare,HTTP Status=403], Issue:
Trace:
@0ms: Making a request to http://pass.zaonpt.com/.well-known/acme-challenge/letsdebug-test (using initial IP 172.67.198.62)
@0ms: Dialing 172.67.198.62
@19ms: Server response: HTTP 403 Forbidden
A and AAAA records found for this domain
pass.zaonpt.com. 0 IN A 104.21.34.50
pass.zaonpt.com. 0 IN A 172.67.198.62
pass.zaonpt.com. 0 IN AAAA 2606:4700:3033::ac43:c63e
pass.zaonpt.com. 0 IN AAAA 2606:4700:3031::6815:2232
Challenge update failures for pass.zaonpt.com in order https://acme-staging-v02.api.letsencrypt.org/acme/order/5751349/2870234144
acme: error code 403 "urn:ietf:params:acme:error:unauthorized": 2606:4700:3033::ac43:c63e: Invalid response from http://pass.zaonpt.com/.well-known/acme-challenge/mfGV0w_xPtFhkgnNhQcsYzhZw-tc7gkvoV_wcvIo5og: 403