Navigate to Configuration then Firewall Configuration
Here you can control traffic between interfaces. Interfaces are defined as SSIDs, VLANs, and any (all interfaces.) Policies are applied on traffic going both ways between selected interfaces.
To Create a Firewall Configuration:
Select the Create a Firewall Configuration button at the top right.
Select the interfaces to apply the policy. Then select either Accept or Deny. By default, all traffic between interfaces is accepted.
Click Create Firewall Configuration.
On the first page, existing configurations can be edited or deleted. This is done under the Action column to the far right.