Basically, there are two to three different indications if your Linksys ac1200 extender is blinking green. That blinks mostly when the AC1200 extender is starting up once you plug it into a power socket. The other case is when you are updating the firmware of the extender and the blinking green light will notify you about the ongoing process. Apart from that, if you are resetting the extender after facing errors in its performance, the same LED will be on the panel. However, it will turn into another light when it is reset completely and you move to the Linksys ac1200 setup. Lastly, when you do the setup using the WPS method you might see a green light on the extender. So, you don’t need to worry about this indication as this will give notifications about the ongoing process.