A test authorization for mrrobotcloud.duckdns.org to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
76.70.59.54: Timeout during connect (likely firewall problem)
Challenge update failures for mrrobotcloud.duckdns.org in order https://acme-staging-v02.api.letsencrypt.org/acme/order/5751349/8558010824
acme: error code 400 "urn:ietf:params:acme:error:connection": 76.70.59.54: Timeout during connect (likely firewall problem)
The IANA public suffix is the TLD of the Registered Domain
The TLD for mrrobotcloud.duckdns.org is: org