My personal recommendation is to: 1. Set password for your WiFi if it doesn't have already (and don't forget to set a complex password, simple passwords are vulnerable to dictionary attacks) 2. Set the network authentication type to WPA and not WEP. WEP are known to be vulnerable to wifi hacking. 3. Hide your WiFi (set your WiFi to hidden WiFi) 4. If you think all the above will still not help, you can set MAC authentication (I personally used to do this together #1 and 2). Mac authentication won't let ppl that have the password use the WiFi unless their MAC address is registered. 5. Add the perpetrators to the WiFi blacklist.