from memory, i think it was like 10 kms (ish), which would cover, umm, probably 300 households (its been several years since looked at it, because, you know, we’ve given up. Starlink got us online)
The rumour at the time was nbn were estimating 3ish million for the job.
But its important to remember that the National Broadband Network is about returning a profit, not providing a service- what kind of dumb idea would that be? :(