Hey,
Try the below:
Check with a different SIM and swap SIM and check for Network Settings
Use Same SIM in a different phone
Run SMMI test to check if there is any hardware fault
Go to Calculator=>type " .12345+= "
you will be entered to SMMI_TEST
How to Enter SMMI_TEST (test hardware)
If you still think the issue persist you can probably wait for 1 software update or visit service center for a check
https://www.asus.com/in/support/service-center/india