Help with blocking internet for single IP's (Dump-AP)

Hello Guys,

is it possible to block single IP's with openwrt in Dump-AP mode ?
Or build an WLAN without access to the internet but into local lan ?

No wan is plugged in, my router run as an AccesPoint...


I think the fastest way is to block the forwarding of packets towards the IP and/or MAC address of the internet router. You may want to allow it for the dumb-AP first if you need it to access the internet.