Fixing OTA Issues in Zigbee2MQTT with Sonoff Ember Coordinator

You’re not alone if you’re using Zigbee2MQTT with a Sonoff Ember Coordinator and experiencing issues with OTA (Over-the-Air) updates failing. Many users have reported that OTA updates do not work with the default settings. However, a simple configuration change that could resolve the problem and ensure smooth firmware updates for your Zigbee devices.

The Problem

The process often fails when attempting to run OTA updates in Zigbee2MQTT with the default settings. By default, Zigbee2MQTT uses the following OTA settings:

ota:
  image_block_response_delay: 250
  default_maximum_data_size: 50

These values may cause issues with some Zigbee devices, leading to unsuccessful OTA updates.

The Solution

The issue can be resolved by modifying the ota section in your Zigbee2MQTT settings. This can be done either by editing the configuration.yaml file or through the Zigbee2MQTT UI under Settings -> OTA Updates. The key adjustments needed are:

ota:
  image_block_response_delay: 200
  default_maximum_data_size: 15

These two settings help in the following ways:

• image_block_response_delay: 200 – Reduces the response delay slightly, ensuring a better timing balance for devices that struggle with the default delay.
• default_maximum_data_size: 15 – Decreases the size of data packets sent during the OTA update, preventing packet loss and improving reliability for devices that cannot handle larger packets.

How to Apply the Fix

1. Via the UI:
   • Open Zigbee2MQTT.
   • Navigate to Settings -> OTA Updates.
   • Adjust image_block_response_delay to 200.
   • Set default_maximum_data_size to 15.
   • Save the changes and restart Zigbee2MQTT.
2. Via configuration.yaml:
   • Open your Zigbee2MQTT configuration.yaml file.
   • Locate the ota section (or add it if it’s missing).
   • Update the settings to: ota: image_block_response_delay: 200 default_maximum_data_size: 15
   • Save the file and restart Zigbee2MQTT for the changes to take effect.

Conclusion

By adjusting these two parameters from their default values, OTA updates should now work reliably with your Sonoff Ember Coordinator. If you’re still facing issues, consider checking your Zigbee network health, ensuring that your devices are within range, and monitoring Zigbee2MQTT logs for any additional troubleshooting hints.

Have you tried this fix? Let us know in the comments how it worked for you!