When you want to use Roamless for data:
1. Go to Device Settings --> Connections --> SIM Manager --> and select Roamless eSIM for Mobile Data 2. Then go to Settings --> Connections --> Mobile Networks
3. Turn ON 'Data Roaming'
4. Lastly please check your APN settings to make sure they match those in the below screenshot.
When you want to stop using Roamless for mobile data, you can undo the previous two settings.
Download:
Setup Guide