hide the ssid of your wifi. It will be a hidden network and only those who know the SSID and Password can have access to it. Google how to do it

Mejemerya be sure that your router's password is different from "admin" cos eyemeta endeza new milew then u can hide ur WiFi (Google it)

Change security policy to WPA2

You can block their mac address. Google how to do that for your modem model

Wifi off adrgew😁