Grandmother's fttc box doing. Info in comments : r/nbn
What you need to know about your Fibre to the Curb (FTTC) NBN connection - DCN Electrical
FTTC (Fibre To The Curb) Setup Instructions - Commander
Set up nbn FTTC | iiHelp
fibre to the curb (FTTC) – BYO modem
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networking - What is a NBN "FTTC Connection Device"? - Super User