---
title: "W55RP20-EVB-PICO and AWS IoT MQTT Connectivity Issues"
url: "https://maker.wiznet.io/forum/15670"
markdown_url: "https://maker.wiznet.io/forum/15670/md"
type: "Forum topic"
category: "Serial-to-Ethernet & ConfigTool"
author: "yhkimwiwave"
created: "2025-04-03T15:00:05+09:00"
last_activity: "2025-04-03T15:00:05+09:00"
language: "en"
views: 10
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W55RP20-EVB-PICO and AWS IoT MQTT Connectivity Issues

## Question

Asked by yhkimwiwave on 2025-04-03 in Serial-to-Ethernet & ConfigTool.

I'm encountering difficulties establishing an MQTT connection between my W55RP20-EVB-PICO and AWS IoT, despite following the setup guide
at https://docs.wiznet.io/Product/ioNIC/W55RP20/W55RP20-S2E/mqtt-connection-guide-en.

Setup Details:

Hardware: W55RP20-EVB-PICO with W55RP20-S2E_Bin_Files_V112.zip.
Process: Firmware flashed, MAC address configured and verified via wizconfig,
AWS IoT thing and certificates set up and downloaded.
Configuration: MQTT settings applied using wizconfig_s2e_tool_1.5.6.3.
Communication: Serial communication via DATA_TX (GP4) and DATA_RX (GP5) on the W55RP20-EVB-PICO.

Observed Issue:

No data exchange occurs during MQTT publish/subscribe tests within the AWS IoT test client.
The AWS IoT test client's topic subscriptions do not receive messages from the W55RP20-EVB-PICO.
Conversely, the W55RP20-EVB-PICO does not receive messages published from the AWS IoT test client.
Switching between MQTT5 and MQTT3 protocols did not resolve the issue.

Inquiry:
What could be causing this communication failure, and what troubleshooting steps should I take?"

## Replies

### Reply 1 (verified answer) by WIZnet AI assistant (automated answer), 2025-04-03

Thank you for reaching out about your MQTT connection issues between the W55RP20-EVB-PICO and AWS IoT. Based on your detailed description, I can suggest several troubleshooting steps to help identify and resolve the communication failure. First, let's verify some key aspects of your setup: 1. Certificate Configuration: - Ensure all three certificate files (Root CA, Client Certificate, and Private Key) are properly loaded into the device - Verify the Root CA section is correctly configured in the Certificate Manager tab - Confirm you've pressed "Save to device" for each certificate and "Apply settings" afterward 2. MQTT Configuration: - Double-check that your Client ID matches exactly with the Thing name you created in AWS - Verify the endpoint URL is correctly copied from AWS IoT - Confirm port 8883 is being used for secure MQTT connections - Ensure the Topic paths are correctly formatted (e.g., $aws/things/your_thing_name/shadow/update) 3. Network Connectivity: - Verify the device has a stable network connection - Check if the device can successfully connect to other services or websites - Ensure no firewall is blocking outbound connections on port 8883 4. Specific Troubleshooting Steps: - Check the device's status indicators - does it show as connected to the MQTT broker? - Try simplifying your topic paths temporarily for testing - Monitor the serial output for any error messages during connection attempts - Verify AWS IoT policy permissions allow publish/subscribe on your topics - Try using the AWS IoT MQTT test client to both publish and subscribe to the same topic 5. Firmware Considerations: - Consider trying an older or newer firmware version if available - Ensure the firmware you're using (V112) fully supports MQTT with AWS IoT If these steps don't resolve the issue, please provide: - Any error messages you see in the serial terminal - Screenshots of your configuration settings - The exact topic strings you're using for publish/subscribe This will help us provide more targeted assistance for your specific situation. WIZnet AI Support Team

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Source: https://maker.wiznet.io/forum/15670