NBN Co expects just 24 percent of fibre-to-the-node lines will be capable of wholesale speeds of 100Mbps or more by the end of the rollout in 2020.

The figure is the lowest for any access technology apart from satellite, with even the fixed wireless network expected to be able to support 100Mbps or more speeds in at least half of all cases.

The whole-of-network FTTN number presents a vastly different picture of fibre-to-the-node compared to its launch back in September 2015.

NBN Co’s chief architect at the time, Tony Cross, said the company’s “FTTN end-user trials have been hugely encouraging in showing that FTTN can deliver great speeds to Australians, with most end-users on the trial getting wholesale speeds of 100Mbps (download) and 40Mbps (upload)".

But hopes of extrapolating the “most end-users” trial result across the production network had hit a snag by mid last year, when it was revealed only 32 percent of FTTN lines could support downlink speeds in excess of 75Mbps.

New figures released late last week show this dwindling further to 24 percent for downlink speeds in excess of 100Mbps.

This figure has not previously been made available.

NBN Co does not specify just how far above 100Mbps some of these FTTN lines are capable of going.

However, the 24 percent figure is based only on the part of the connection that NBN Co has control over; it “does not account for constraints imposed by RSP or purchased CVC capacity” or “for constraints imposed by end user premises equipment or in-home network”.

Those factors have caused their own problems: NBN boss Bill Morrow last year said up to 75 percent of FTTN users that paid for 50Mbps or 100Mbps retail services never saw that “absolute” topline speed - though he claimed they may not be far enough off it to care.

Other fixed fares better

Comparing other fixed-line access technologies, NBN Co claims all of the FTTP, FTTB, FTTC and HFC parts of the network will be capable of “layer two speeds of 100Mbps or more by rollout completion”.

Of the FTTC expectation, NBN Co said it assumes it will "reactively upgrade any VDSL-only FTTC footprint to G.fast as required to meet customer service requirements".

The FTTC network itself is not yet live but should be opened sometime around the middle of this year.

G.fast is expected to appear in the network in the second half of this year.