Juniper SSG5 configuration with Unifi, Where to tag the VLAN 500

Hi Guys,

Right now im working on a PPPoE configuration for Unifi to work with Juniper Firewall SSG5.

Currently, the setup is using:
DSLAM ---> HUAWEI HG655a ----> TP-Link Router -----> LAN

So now I were to change it to:

DSLAM ---> HUAWEI HG655a ----> Juniper SSG5 -----> LAN

As I know the TP-Link router will hide the VLAN ID while doing the PPPoE therefore we only input the username and password for unifi it will do the rest. But if we were to change it like in my case using Juniper I should find the pppoe interface to attach it with VID 500. But so far I could not find that option.

I have dealt the same thing using Fortigate and the Fortigate allow or has the option to attach VID into the pppoe wan (pppoe) interface.

Have you guys configured unifi with Juniper? If yes please share how you attach the VID.

Appreciate of any of the reply.

Thank you