Broadband modems supplied by Australian internet retailers are incapable of delivering 100 Mbps download speeds over the average fibre-to-the-node connection, according to the consumer watchdog's own performance testing.

At the same time, poor Wi-Fi performance from supplied modem/routers is another key bottleneck stopping Australians enjoying their promised NBN speeds.

Testing of 43 modem/routers from 11 different hardware makers and 10 internet providers, found that none could achieve 100/40 Mbps broadband speeds over a 450-metre copper run, which is the average length of copper in an NBN FTTN connection.

Customers may not be able to achieve the speeds they pay for. Supplied

At this distance from the node, download speeds vary from 60 to 94 Mbps and upload speeds from 10 to 29 Mbps, according to an independent modem/router performance testing report commissioned by the Australian Communications and Media Authority.

Illustration: Matt Golding

A third of Australia's FTTN NBN connections rely on more than 400 metres of copper, with the report finding a significant performance drop at the 450-metre mark. The ability to cope with a poor copper connection varied widely between modems used on the NBN.

At the 1050-metre mark — with additional line noise added to simulate a poor-quality copper line, electrical interference and shoddy installation work — download speeds vary from 10 to 29 Mbps, while uploads only hit 6 to 9 Mbps. The quality of the copper connection and the variation in modem performance means these speeds fall far short of the 50/20 Mbps speeds which NBN is pushing as the standard broadband connection.

Along with assessing a modem's ability to offer a fast and reliable NBN connection, testing also looked at its Wi-Fi performance for providing internet access to wireless devices around a home.

Wi-Fi performance varied significantly across the devices tested, which looked at both the 2.4 and 5GHz Wi-Fi bands over short and long distances, as well as the impact of interference and obstructions such as walls. The report found that more expensive Wi-Fi-enabled modems do not necessarily deliver greater speeds and range.

While 5GHz Wi-Fi offers faster speeds than the 2.4GHz band, 5GHz performance is generally considered to be more affected by distance and obstacles. Despite this, the report found that most 5GHz Wi-Fi devices tested provided better performance through walls, and at a greater distance, compared with their equivalent 2.4GHz performance.

There was considerable variation in the performance of all devices when operating on the 2.4 GHz band. Some devices could barely break the 50 Mbps mark, whereas others achieved close to 160 Mbps when transferring files from a network storage drive.

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This large performance gap was likely due to compatibility issues between a consumer’s modem/router and their Wi-Fi devices; particularly older laptops, phones and computers, according to the report. The issue is likely to result in some Australians being "unable to achieve optimal performance" of their FttN NBN service.

"Better Wi-Fi performance, and consequently better NBN performance, would be achieved by choosing a device using the 802.11ac standard (or next generation 802.11ax, also known as Wi-Fi 6) operating in the 5 GHz band," according to the report.

The modem/router performance testing report may become the basis of a push by the ACMA to force Australian internet providers and modem makers to declare real-world modem/router performance figures, in line with their obligation to declare the real-world performance of NBN connections running to homes.

"The outcomes of the study have informed the preparation of practical consumer information and guidance to assist consumers in making well-informed decisions in purchasing, setting up and using Wi-Fi modems," according to the report.