Hi @satebabi889 . Are you using the TPG VOIP phone service with your phone connected to the VR1600? If you are, the VR1600 must stay in normal mode, not bridge mode, and it must be connected to NBN box.
If you do not use the VOIP phone service, consider connecting the Orbi to the NBN box. Its wifi might be sufficient by itself. Do a factory reset to get it back to normal. You need to set VLAN ID=2. See this section in the manual:
Set up a bridge for a VLAN tag group.
@satebabi889 . With fttc, nbn box is modem, orbi is router. Archer not needed.
Look at archer config. Put these settings in orbi. PPPoE. Userid as shown in archer and password.
The orbi manual has instructions on setting vlan id.