ESP32 AWS IOT Data Missed while receiving data from broker

[mustray]

Hi,
I am working on ESP32 IDF-MQTT_3_1_1,using the subscribe_publish example modified to accept data via second uart. While publishing data (using Qos=0 or Qos=1) to the aws iot host, out of every 100 packets 4-10 packets are missed. Similarly when am receiving data on the subscribed topic, data is missed. Also my aws mqtt disconnects frequently and as auto_reconnect is enable it reconnects again.
What could be the possible reason.
Any help is appreciated.