Sophos UTM: WLAN AP`s - a new wlan that connects to another subnet on interface . howto?

hi. this is translated from german to english_

Hello, we currently operate a UTM firewall quite simply:

The Sophos is connected directly to the internet modem. The internal network of the UTM is 192.168.0.1/24.

We use Sophos Access Points. The access points have an IP address in this network. there are two wlans:

VANS_Hotspot (on wlan0) SSID: VANS_Hotspot Encryption: No encryption Frequency band: 2.4 and 5 GHz separate zone

VANS_Safe (bridge to AP LAN) SSID: VANS_Safe Encryption: WPA2 Personal (using AES) Frequency band: 2.4 and 5 GHz bridge to ap lan

now another network (192.168.103.0/24) is to be connected to interface 0 - or it is connected. i have set up a new interface in sophos and assigned a fixed ip (192.168.103.85).

ping from 192.168.103.x network to interface works.

our goal now is that we can broadcast another wlan on the access points, which allows the wlan clients to connect to the network on interface 0. there is a dhcp server (not sophos, but windows server) in that segment - this should assign the ip addresses for 192.168.103.x. and only this wlan name (e.g. "WLAN-192.168.103.x") should establish a connection to the network on eth0. unfortunately i can't really find how to do this in the wlan settings.

thanks