As per checking, TPG supplied modem does not currently support TP-Link Tether app.
This link may provide further information: https://www.tp-link.com/au/tether_compatibility_list/
Are there any plans to enable the tpg modem to be controlled by the Tether app? Given that many other modems on the market provide an app to control various functions, I'm surprised that the tpg modem is not included.
There would be many many parents, myself included, who would make use of the parental control features, which is VERY difficult (and impossibile on a mobile) through the existing management interface.