webapps blocking my ipad if the website is not online.

Hello,
I developed a webapplication that runs on a local network. After running my webapps and add on the home screen of my ipad all running smoothly.

By cons when I run the webapps from another internet connection outside of my local network that does not work (normal). My problem is that the iPad shows a white screen and is totally blocked, unable to return to the home screen, have to force a restart of the ipad ...
Do you have any idea how to work around or fix the problem please?