This article applies to:

Deco M9 Plus V1/V2(mostly V2)

Issue phenomenon:

Deco M9 Plus starts to have flashing red issues after upgrading to 1.5.1 (or later) firmware. Certain satellite units will turn flashing red, disconnected from the main Deco, and clients connected to it will lose Internet. It won't be able to recover until the unit is rebooted manually.

Available Solutions:

If you encounter a similar issue after updating the Deco M9 firmware, please install the new firmware below to monitor again:

For Deco M9 Plus V1: 

https://static.tp-link.com/beta/2021/202106/20210603/Deco_M9 Plus_V1_1.5.1_20210520_awn_apsd_offline.zip

For Deco M9 Plus V2:

https://static.tp-link.com/beta/2021/202106/20210603/Deco_M9 Plus_V2_1.5.1_20210520_awn_apsd_offline.zip

 Note:

1. The above new firmware could be updated through http://tplinkdeco.net, and there is an upgrading instruction in the zip file.

2. Please check the firmware version in tplinkdeco.net or the Deco app after upgrading the new firmware, making sure all Deco units are properly upgraded. The new version should be 1.5.1 202110520.

3. This firmware can be rolled back to the previous official version.

If the issue is not resolved with this new firmware, please send an email to support@tp-link.com with the subject [Forum ID 266974] Deco M9 Plus satellite units flashing red after upgrading 1.5.1 firmware and provide us the following information:

• TP-link ID;
• the network topology of the Deco system;
• the satellite flashing red frequency (like 3-4 times every day);
• the mac address of the flashing red satellite unit. 

For other dropping issues which are not mentioned here, it is NOT recommended to update this firmware. Please refer to this FAQ for further troubleshooting: https://www.tp-link.com/support/faq/2428/.