Hello,
JIO operator is LTE only. So in order for it to work need to enable VoLTE. This setting can be configured in Network -> Mobile -> General section.
If that does not help, you may need to perform modem module firmware update. However, before that, I would like you to attach a troubleshoot file to your question, to review your device. Before generating the file, please replicate the issue, then access router's WebUI, go to System -> Administration -> Troubleshoot section and download troubleshoot file from there.
Best regards,
