For Android phones, following settings should be carried out -
1. SIM Card to be placed in LTE enabled SIM Slot.
2. Internet should be routed through Jio Network.
3. Set the Network Mode to LTE/ 4G
4. Ensure Mobile Data is on and Data limit is disabled.
5. To enjoy uninterrupted Internet Service while roaming, keep the option of mobile data while roaming 'ON'.
For Apple phones, Just ensure your Mobile Data is on.