Evothings applications running in the viewer are served over HTTPS from our proxy servers in the cloud. This means any connections made from the application must be secure. Your application must use HTTPS or WSS (Secure Web Sockets) with the server presenting proper (not self signed) certificates that includes all intermediates - in other words, the full chain of certificates. The reason for needing the full chain is because the viewer doesn't have a lot of trusted certificates bundled with it like a normal web browser does. For more information see our IoT Cloud Starter Guide.