Make XG Port act exactly like RED device

Hello community,

I have a UTM 9.7 in our HQ. Also I deployed several RED devices in our branch offices.

On UTM side I got an ethernet bridge over all connected red devices and eth5 of the SG.

In the RED configuration I put the RED Clients in VLAN mode and defined the VLANs the RED should have as trunk on its LAN port.

All necessary firewall rules on UTM side are defined.

RED to UTM traffic works as intended.

Now the question(s):

What do I have to configure on my XG to act the same way a RED devices does? I can't find any details/docs for my exact use case.

I created a RED tunnel between UTM and XG that is also up and working.

I am able to ping from the UTM bridge interface to the XG RED interface and vice versa.

How do I manage to set up the following connection (like a RED devices works)?

UTM [VLANs/eth5 -> Bridge(10.200.200.1)] -> Internet -> XG [RED Interface(10.200.200.31) -> Port1 -> VLANs]

I hope you understand what I am trying to achieve.