Hi  @Pabery,

Is it your first time to set up range extender?

TP-Link range extender works with almost any Wi-Fi router and is easy to install. There are three ways to connect the TP-Link Range Extender to a router. Before you start, please power on the extender next to the router:

1. Via the WPS button, there is a physical WPS button on the Range Extender. Press the WPS button on the Router, and the Range Extender in turn. The Range Extender will connect to the Router automatically within 2 minutes. If the router doesn't have a WPS button, you may try the other two methods instead. For detailed instructions, please refer to:

Configure my Range Extender via WPS button

Alternatively, here is a full setup video for your reference:

How to set up a TP-Link Range Extender

  @Joseph-TP 
Hi Joseph, thanks for your support.
I have tried in every way, via the app and via the extender website but it cannot connect to the internet in any way.
As regards the first step, by connecting it near the modem, only the first two lights, power and wireless, come on steadily, while the 'RE' light remains flashing