Hi,
1. Make sure you don't have a manual operator selecting enabled and everything is on Automatic there.
2. Check if your mobile APN isn't set to the old SIM card one, use the new custom APN that your new internet provider gave you.
3. Make sure you don't have frequency bands locked as the new internet provider might not support the ones you have selected. Keep that on automatic.
4. Update your firmware to the latest available one to avoid any issues that were happening before.
EB.
