React Native App Android - Cannot access the 3G/LTE internet

We have a react native application using Expo . The application works fine using wifi , but when trying to work with 3G/4G only the app cannot connect to the internet/web services .

When the wifi is turned on , we can start the mobile app , turn off the wifi (app is still open) with only 3G available , the app continues to work . But the when the app starts if there is no wifi and only 3g it is not able to connect to the internet .

Crrently tested only on the Android Phones.

Any advise on how to resolve this will be much appreciated