xr500 block access to network?

i am wondering if there is a way to block access to devices or "unknown" devices from the LAN.

i know i can check the block device box and it wont be able to access the internet, but you can still access the LAN.

i tried it with the "traffic controller" tab and picked block and reject all traffic, but the device was still able to connect to wifi and access lan computers.

sure i can change my wifi password and keep devices i dont want off, but i was wondering if there is an option in software. 

the reason is i think someone has hacked my WIFI. i have sometimes a connected device i dont recognize pop up and i checked block but its still connecting. 

changing the password would only be temporary as wifi is very insecure. 

id really love to set the router up as a whitelist only as i only have a few devices, but i dont see an option for that at all. only option is to block or reject certain devices not all.