A test authorization for iseries.world to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
99.247.240.88: Fetching http://iseries.world/.well-known/acme-challenge/Ubirb_GaF7n_dLS_DxEDssEtlGJOjSX399xIzd8q8Dc: Error getting validation data