I have bought three Meizu devices of same model - Meizu M3 Note (India)

Am facing intermittent network disappearance and fluctuation issues. Issues occur most of the time while:

• trying to call
• receiving the calls
• during the calls
• in standby mode
• While unlocking or using the phone after interval of 30 minutes or more
  

Have tested different stable versions on my devices to mitigate the network issue being caused because of software or firmware issue, still the issue persists.
Flyme 6.2.0.0G (2017-12-26) stable
Flyme 6.3.0.0G (2018-4-17) stable

Have given the device to official Meizu support centre(Electronic Technology India, mahalaxmi east) on two occasions still the issue persists.

Am unsure whether its a model specific hardware or software issue, Meizu kindly fix the issue to the soonest.

Though the build quality and features are excellent on M3 Note, however the basic functionality of making and receiving calls have been compromised, really disappointed buying three devices of same model.

have attached screenshots of network issue.