Name the symptom
No signal, failed calls, delayed texts and slow internet are different faults. Note whether one line or both lines on a dual-SIM device are affected. Check official service status before assuming the handset has failed.
Try the small changes
Restart the phone, briefly use flight mode and verify the selected data line. Check allowance and account restrictions. Follow the manufacturer’s instructions for the model rather than entering network settings found in an unrelated forum.
Avoid difficult reversals
Do not start by factory-resetting the device or deleting a working eSIM. Backups and recovery access matter before disruptive action. A network-settings reset can remove saved Wi-Fi information. Give support a short log of the tests already performed.