.day domain names are an encrypted-by-default TLD by virtue of being inscribed in the HSTS Preload list.
As such, websites hosted on .day will not load on modern browsers unless they are served over HTTPS (ie. with an SSL certificate).
Before a .day domain name will resolve in browsers an SSL certificate will need to be installed. Conetix offers FREE SSL certificates for Domains with DNS hosting through Conetix.