The INPLUG will only work with a 2.4G WiFi network.

Make sure the AP isolation function is deactivated.

Make sure there is no login page needed to connect to the router.

Make sure the SSID for the 2.4G network is different from the 5G network if you a have dual band router then operates with a smart dual band system (BT Infinity 4 or 5 Hub for example.