MQTT protocol add EC2

Verify that your EC2 security group allows inbound traffic on the MQTT port (typically 8883). You may need to open this port instead of using the sudo ufw allow mqtt command.

Confirm that your device certificate and private key have been attached properly to your AWS IoT thing and that your client code is using these credentials correctly when connecting.

Consider using MQTT over WebSocket which can bypass port restrictions by tunneling over port 443. The AWS IoT Device SDKs support this out of the box.