BasilDV explanation on how to Bridge the TP-Link VR1600 modem/router looks helpful and I will try it when my line is changed over from ADSL to NBN FTTN on Friday so that I can continue to use my Asus RT-AC66U.
My question is - will the Phone connection on the TP-Link VR1600 modem/router still work, or will I loose my "fixed line" as it were.?
If you bridge the TP-Link VR1600 modem/router, the phone service will not work as the authentication for the SIP settings will need to come from the TP-Link.
If you want to use the Phone service, then you have the option to use your own modem/router as an access point.