@Wobblyman 

Thanks for reaching out. I understand that you are experiencing ongoing connectivity issues with your 2.4 GHz IoT downlights connected to your Deco Mesh network, particularly with devices connected to the furthest Deco unit (BE25), which tend to drop off and do not reconnect automatically, even though they show a strong signal and have static DHCP addresses.

Here are some steps and recommendations to help address these issues:

Main Deco and Satellite Deco Troubleshooting:
• Placement: Ensure all Deco units, especially the satellite (BE25), are placed in open areas and not inside cabinets or corners. This helps maintain optimal wireless backhaul and client connections.
• Signal Strength: Move the BE25 closer to the main Deco units if possible. The ideal backhaul signal strength should be at least 2/3 bars.
• Ethernet Backhaul: Since your BE65s are wired, ensure the Ethernet cables are in good condition and securely connected. For the BE25 (wireless), try temporarily disconnecting any Ethernet cables (if present) to see if this resolves the issue.

2.4 GHz IoT Device Stability:
• Channel Width: You have already set the 2.4 GHz channel width to 20 MHz, which is recommended for IoT stability. Avoid using 40 MHz, as it can cause more interference.
• Network Optimization: Use the 'Network Optimization' tool in the Deco app to automatically optimize your 2.4 GHz Wi-Fi channels.
• High Capacity Mode: If your Deco model supports it (mainly Wi-Fi 7 models), go to Deco app > MORE > Wi-Fi Settings > Advanced, and enable 'High Capacity' mode for 2.4 GHz. This can help with congestion and improve device stability.
• Device Roaming: IoT devices may not always roam efficiently between Deco units. Some IoT devices tend to stick to the first access point they connect to, even if another unit offers a better signal. Unfortunately, this is a limitation of many IoT devices and the 2.4 GHz protocol. If your devices are not reconnecting automatically, try turning the device's Wi-Fi off and on, or power cycling the device to force a reconnection.
• Number of Devices: If you have a large number of IoT devices and Deco units, try temporarily powering off some units or devices to see if stability improves.

General Checks:
• Parental Controls & Access Control: In the Deco app, ensure that your IoT devices are not restricted by Parental Controls or Access Control lists.
• Firmware: Make sure your Deco units are running the latest firmware version.

If the issue persists: Please contact TP-Link support and provide the results of the above troubleshooting steps. This will help us further diagnose and resolve your issue.

Note: 2.4 GHz technology and IoT device roaming behavior can be inherently less reliable than 5 GHz/6 GHz, especially in complex mesh setups. Some IoT devices are not optimized for seamless roaming and may require manual intervention to reconnect.

For more details, you can refer to the official FAQ: https://www.tp-link.com/en/support/faq/2925/

If you need further assistance, please let us know!