A test authorization for rdsgw.elgo.be to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
Fetching http://rdsgw.elgo.be/.well-known/acme-challenge/eTmQnNxp1EZuNLzEBi6dAQ31Zzbgzl1IiIJVf4euYEU: Connection refused