"The TPG figures are even worse than those obtained by the Senate showing

the average HFC connection experiences 11 times more network downtime

than fibre to the premises," she said.

"There is no question the decision by the Liberals to force NBN to rely on ageing HFC infrastructure has been a costly and unnecessary mistake."

Labor, which conceived and launched the NBN in 2009, had planned to roll fibre-optic cable to every premises in Australia. But the Abbott government scrapped this plan in 2013, replacing it with the "multi-technology mix" that included HFC and fibre to the node.

NBN Co defends 'complicated' HFC technology

NBN Co rejected claims HFC technology was failing. An NBN spokesman said HFC technology differed from fibre to the node and fibre to the premises, because it often required the NBN to split the node to add more capacity. He said that inevitably caused temporary outages.

He said the technology was complicated by the fact that the coaxial cables are shared with Foxtel, meaning NBN has access only to some of the bandwidth within those cables. He said Foxtel will vacate the cables by 2023, which would free up capacity.

But in an effort to avoid more outages, he said NBN Co was investigating "the feasibility of incorporating greater power resilience capabilities to better support HFC network infrastructure in the event of a mains power outage".

"We are planning to commence a small-scale trial this financial year and we hope to gain deeper insights and validate the anticipated costs and benefits of enhanced power resilience at scale across the HFC network."


Nevertheless, the comments will feed into the narrative that NBN's technology is not up to scratch, strengthening the case for players like TPG-Vodafone, Telstra and Optus to offer 5G fixed wireless alternatives. All three have signalled an interest in offering 5G fixed wireless, with Optus having already launched a product in limited areas.

As of June, just under a million households were connected to the NBN by HFC. By the end of the switch-over, that figure is expected to be up to 2.5 million.

The comments come after Telstra announced it would no longer provide NBN's top 100 megabit per second plan to customers on fibre-to-the-node technology.

Mr Penn said FTTN, which mixes fibre and copper, was "just not capable of providing that speed".

"Moreover, NBN is not capable of telling us that until we actually connect the customer," he said. "It's a painful customer experience. So until we can actually see whether that experience can be improved then that's the decision we've taken."