We don't normally support NON-TPG modems, but we will try and help.
''Tricky Settings'' on setting up NBN modems start with the VLAN. In modems, it should be set to VLAN ID 2.
PPOE is another.
Manually putting in your username and password will be required also.
You may need to browse your modem manufacturers pages for further info.
If you get stuck, you can use the TPG supplied modem so you can use the Internet.
Do you intend to ditch the Archer and Netgear and use just the Asus connected to the NBN box?
The Asus manual makes no mention of vlan id.
It does have auto detect. Connect Asus to nbn box and press reset. Logon to router and you will go to the setup wizard.
Select PPPoE and enter TPG username and password.
The router system log (Advanced Settings) might indicate any problem.