In order to let EasyCron connect to a particular IP to execute a cron job, you can
For example, if your cron job URL is https://www.example.com, the particular IP is 93.184.216.34. You should add https://93.184.216.34 as cron job URL, and in the "HTTP" tab -> "HTTP headers" field, add Host: www.example.com.
In this way, EasyCron will use the specified IP (and the domain name) to connect to your website and execute the cron job on the server bound with that IP.