troubleshooting_device_connections

Troubleshooting ESP8266 and ESP32 connection issues.


1A.  Make sure you are on a 2.4GHz network not 5GHz, the device only communicates at 2.4GHz

1B.  Make sure the your device AWS endpoint region matches the current AWS region in your console on the browser

1C.  Use the 'ATS' AWS endpoint from IoT Core--> Settings or: aws iot describe-endpoint --endpoint-type iot:Data-ATS

2.  Make sure port 8883 isn't being blocked by your network admin, this is the port that MQTT(s) traditionally communicates,
    AWS IoT Core requires you send MQTT data over secure port 8883 or 443

3.  Make sure your onboard device certificates match your AWS IoT Core region, the x509 should be fungible between regions

4.  Make sure you attached an AWS IoT Policy to your security certificates.  If you have not you will see the connection on the 
    monitor tab but no data will appear on the MQTT test console.

5.  Don't exceed your Char, sprintf, or snprintf buffer.  MQTT requires payloads get sent by time and size over cycles.
    if you overload the buffer it may not transmit or receive the payload.   To solve this issue for large payloads you
    can also increase the size of your MQTT BUffer by changing the value of MQTT_MAX_PACKET_SIZE in PubSubClient.h from 128 to 512.
    to solve this issue.  This bigger payload allocation will allow longer variable names to transmit.  If you use the alternate ESP32
    In the alternate ESP32 sketch on my github the buffer is set to 512 automatically by this line:  MQTTClient client = MQTTClient(512);
    This alternate ESP32 sketch uses a different PubSub/MQTT library but operates fundamentally in the same way

6.  If you aren't receiving your devices payload under your subscription topic in AWS IoT Core in the "test" tab,
    then go to the "Monitor" tab and see if your device is even connecting.  Often a device is actually connecting,
    but the payload isn't being received, the reason for this  is usually a problem with your device certificates.
    The device will connect but the payload wont pass through if your device certificates aren't exactly correct.
    If your device isn't even ahowing up in the Monitor then it is likely a hardware issue not a certificate issue.
    Confirm you are using the correct virtulization package or board manager for your device.

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Some older or cheaper ESP32 Boards:

Connecting........_____....._____....._____....._____....._____....._____....._____....._____....._____....._____
A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header

Solution:
while connecting holding down the Boot/EN button for one second initiates the firmware download mode
BOOT = FLASH: if you hold it down and press the EN/RST, your ESP32 will restart in flashing/uploading mode
Do not press the RESET Button