I am curious as to why you are trying to get to a site via an IP address rather than a URL. Access to any site, to test it for public access, would need to be done via URL as 99.9% of the population would be accessing the site via the URL address. To test it through any other means would now be really helpful in making sure it can work via another device.
Here are a few places to test the site on multiple devices.
http://mobiletest.me/
https://www.browserling.com/
http://browsershots.org/