1. You probably didn't whitelist properly.
See the docs of npm's cordova-plugin-whitelist.
2. Be aware that both Google and Apple will most likely reject an app which is merely a website wrapper, due to their review guidelines.
Thanks very much, that's exactly what was wrong.
The app is not destined for public use so the appstores are not an issue, it's just for internal use.
Thanks again for your help.