Should I buy my own NBN Modem?

The answer to this depends on wether your ISP supplies a modem with their internet service. But I would generally so NO

For Example, Telstra supply their own modems which are hard wired to their services. If you buy your own modem with a Telstra service 1) Good look find the information to set the modem up and b) When ever you encounter a problem, the Telstra techs will point the finger at the “non-telstra” modem.

The biggest complaint with ISP modems is the poor quality of the Wi-Fi.

This is easily fixed by purchasing a seperate Wireless Router (such as the AmpliFi HD) or Wireless Access Point (WAP) and plugging them into the ISP supplied modem.

You should also disable the Wi-Fi service on the ISP modem and only use the Wi-Fi network being produced by the WAP or Wireless router