Hi @manuav,

Here are some suggestions for your issue:

    a. 2.4G light not up means the extender is not connected to the router. Connect your phone to the host router's Wi-Fi to verify it's working.

    b. Forget the router's Wi-Fi on the phone and try reconnecting to ensure the Wi-Fi password is correct.

    c. Change the router's 2.4G Wi-Fi channel to 1/6/11. You may refer to this link or contact router support to change: Changing Channel and Channel Width on a TP-Link Router (new logo)  

    d. Disable security settings like Mac filtering or Access Control on the host router. Please contact the router support for guidance.

Note: If there is more than one extender, ensure that their Wi-Fi names are different from the main router's so that they can connect to the router's Wi-Fi without issue. Follow this link to change the extenders' Wi-Fi name: How to change wireless settings of TP-Link range extender on Tether APP