The blinking blue light on the Deco signifies that the mesh system is ready for the setup process. However, when this light turns solid blue, it means that the TP Link Deco setup is going on. But, there are times when the Deco keeps flashing blue even after the setup process. If you too are complaining about your Deco blinking blue, you should read the post. https://deco-mesh.net/why-is-my-deco-blinking-blue-even-after-deco-setup/