The settings are PPPoE, your username with @TPG.com.au on the end and password and VLAN ID=2.
I couldn't find the manual for this router, so if you can't find a setting for VLAN ID, it can only be used as an extender to the TPG router. If you find anything to do with IPTV, you could see if that has an effect.
Have you contacted the manufacturer of the device to assist you or guide you on how to set the VLAN ID for it? If not, then changing service provider will not help as the same technology will be used.
There's a possibility that you are required to set the VLAN ID again.