Create a separate wifi without Access to other lans

Hi everybody,

I want to have a WIF in my sophos xg 115 without access to any other network in it.

I created a "separate zone" wifi and added it to local Access point. After that, i created a new dhcp for this wifi.

After all, i have a functional wifi, i can connect to it and Access google, but i can ping to other LAN's that i have in the firewall too, and id like to deny that Access to other networks...

Is that posible? And how can i do it?

Thanks.