[USG Flex H] - Cannot use Policy Control between devices in the same Zone

Hi @Maverick87

This is because Intra-BSS traffic blocking only blocks unicast packets. If the printer use mDNS to provide its info, it will be forwarded.

However, since the devices are all connecting on the same AP, to control the traffic in the same VLAN will only use the function "Intra-BSS traffic blocking" for device in same SSID and "Layer 2 isolation profile" for device in uplink.

Differences between Intra-BSS Traffic Blocking and Layer-2 Isolation — Zyxel Community

In addition, If the devices are connecting under a switch, you can check if the switch supports to set ACL/policy rule to block the traffic. But you still need to know the traffic path to set the rules.