Improving ADSL Performance

Recent events caused me to re-visit my ADSL connection, and my experiences with what I found may help others here. This article can be found online at


I’ve been an Orcon customer for many years, and have had a broadband connection through them since the old Jetstart days, probably around six years ago. Quite a few changes have happened to ADSL in NZ over that period, but apart from one change to the plan I was on,  and having to replace one broken router, I’ve always viewed broadband as something that happened in the background and never thought too much about it – it’s there, it’s always on and it works, so it doesn’t require any attention.

Recently, however, my speeds dropped back to what I was actually paying for (other Orcon customers have noticed this, too) and 256k downloads/128k uploads (while fine six years ago) really are painfully slow when using the internet today. Files are much larger, websites are more complex, more data is sent in both directions, and there is a more video and other streaming content – at higher resolutions – which places a lot of demand on bandwidth. There are also more network-connected PCs and other devices at home, all independently doing their own thing using ADSL.

My ADSL connection is always on (“nailed up” is the term sometimes used) and I treat it just as I would any other utility. I’ve never been able to understand the reasoning behind switching off ADSL when nobody is using it – it’s like unplugging your house from the mains or turning off the water until its time to do the dishes or have a shower.

I upgraded from the plan I was on to full speed in both directions – both down and up. Although it costs more, full speed up has a number of advantages – and not just reducing the time it takes to send large emails, upload photos and videos. For example, Bittorrent clients can be run with decent share ratios – in fact it is necessary to manage upstream traffic carefully to avoid exceeding the data allocated to your plan.

I live quite close to a reasonably modern exchange, and after upgrading my plan I was still not getting the speeds that ADSL is currently capable of. A further increase in speed was achieved by upgrading the firmware in my router (now five years old) to make it ADSL2+ capable. Even more speed was achieved by upgrading to newer hardware, with still further increase in speed achieved by upgrading the firmware on that hardware.

In my experience


Gets you about 256kb/s (32kB/s) downloads and 128kb/s (16kB/s) uploads. This is slow even when just web browsing, and pretty much precludes listening to internet radio or downloading files while trying to do other things with the network connection.



Speedtest FS/128 Oceania

Speedtest FS/128 USA

This is what many of Orcon’s 256/128/40GB customers have been actually getting for the past few years, at no extra cost.

Gets you a boost on download speed to 3.5Mb/s to 4.0Mb/s which is significantly faster than 256/128. Uploading content is still painfully slow (and the internet after all, is supposed to be a two way medium). It is possible to do multiple bandwidth intensive tasks without problems – except for Bittorrent.

Bittorrent is a two-way protocol, and your download speeds are restricted by the client if you have poor share ratios. It is also worth noting that if you don’t restrict your upload speeds to around 8kB/s (say half of your upstream bandwidth) you will notice that your Bittorrent download speeds will drop off quite markedly. This will also affect other uses of the network, with website timeouts and slow page load times.

However, ADSL2+ is supposed to be capable of 24Mb/s download speeds (if you live inside the exchange itself). ADSL2+ Annex A (used in NZ) is capable of about 900kb/s upstream (Annex M, used overseas is capable of up to 3.5Mb/s)

It could be suggested that ISPs are deliberately restricting users to 128kb/s upstream connections (rather than 256kb/s) because the lower upload speed happens to restrict download speeds to around 4Mb/s – and thus reduces data usage by customers and bandwidth demand. There is a article explaining why upstream speed affects downstream speed at


An immediate improvement to ~6Mb/s download, 0.75Mb/s upload.

Everything runs much more smoothly – it is possible to do just about anything on the network without affecting anything else – listen to multiple radio streams and watch NASATV concurrently, for example. Uploading video takes minutes instead of hours (bear in mind, upload speed is now 3 times what the 256/128 download speed was).



Speedtest FS/FS/ADSL2+ Oceania

Speedtest FS/FS/ADSL2+ USA

A further improvement to 8.2Mb/s downloads, 0.75Mb/s up.

Upgrading the router firmware to a more recent version made it ADSL2+ capable – but be careful, it is possible for firmware upgrades to go wrong and render the router useless. Don’t bother upgrading unless you can afford to replace your router, and that you feel you might get some benefit from the extra speed. For some marginal connections this is probably a worthwhile upgrade.

In use, there isn’t a significant improvement in experience but I assume for multiple concurrent users of the connection there will be some benefit.

Overseas sites are considerably slower than Australasia, around 2-3Mb/s.

This and all previous tests were using a 5 year old TRENDnet TW100-BRM504 router.

New(er) ADSL2+ hardware:

Speedtest FS/FS/ADSL2+ ZyXEL

Installing a used ZyXEL  P-660H-61 produced an improvement in speeds to about 11.5Mb/s down, 0.80Mb/s up.

Latest firmware for ZyXEL:

Speedtest FS/FS/ADSL2+ ZyXEL firmware upgrade

Speedtest FS/FS/ADSL2+ ZyXEL firmware upgrade

This firmware was in fact only released a few months after the original firmware installed in the ZyXEL. Speeds now up to 14.5Mb/s down, 0.80Mb/s up. Interesting to note that speeds are now consistently higher than 11-12Mb/s but vary, possibly depending on network use.

Overseas speeds also improve to 4-5Mb/s in general, again with some variation due to network use.

There is some variation in speeds measured, the above images are all typical but here is my current best result.

Speedtest FS/FS/ADSL2+ ZyXEL firmware upgrade best result

Does it matter?

It is worth noting that the higher speed results are all for local servers but they are consistent within Australasia. However, when testing speeds against servers in Asia, US, and Europe, significantly lower speeds are reported – around 2-4Mb/s in fact.

There are very few servers that will send data to you at the full rate of your ADSL connection, so you’ll see most benefit from the higher speeds if you have multiple concurrent users or consistently run multiple bandwidth intensive tasks. However, I have noticed that for a few tasks, I do get the benefit of the extra speed – when downloading videos that appear in my Miro subscriptions, for example I often see download speeds of 800kB/s, and even as high as 1.4MB/s. Miro uses Bittorent to distribute files, so the aggregate download speed may be being shared by several servers.

Ubuntu updates are served locally from Citynet servers, and I see very high speeds when using them – for example:

Ubuntu update speed

ISPs manage their own network traffic; for example, there seems to be little doubt that Orcon deliberately throttle YouTube traffic which makes videos load very slowly. It may be possible to work around this by using network proxies – much as is used to access regionally restricted websites like Hulu.

In my opinion, it probably doesn’t matter – if you are getting around 6Mb/s you are probably getting what you pay for and are also likely experiencing the level of responsiveness and speed achievable on ADSL as provided by Telecom in NZ at the current time.

However, apart from bragging rights, achieving a higher ADSL speed means you will automatically benefit as NZ’s ADSL network improves in future. It has improved a lot in the past 6 years, it seems likely it will further improve over the next 6 years.

Remember that there are factors other than speed to consider – for some uses (like streaming, Skype/SIP/VOIP, gaming) network latency, packet loss and jitter are also very important. You can test your connection for these factors at


To summarise – get FS/FS, use modern hardware running the latest firmware. Maintain your house phone wiring and make sure you live close to the exchange. Preferably an ADSL2+ capable exchange (though Telecom are installing upgraded street cabinets, too).

The early gains were easy – I just signed up online for a current plan, and for an extra $5.00/month had effectively increased my broadband speed 24 times (256kb/s to 6Mb/s).  Subsequent increases in speed (a mere doubling to around 12Mb/s) cost nothing as I already had the hardware and firmware updates were readily available but required more effort on my part.

If you already have a FS/128 plan I would consider upgrading to FS/FS – depending on your use of course.

It seemed clear that hardware also played a part, so if you are upgrading your router it is worth considering returning hardware that doesn’t perform.

Feel welcome to leave questions, feedback or your own results in the comments.


All tests were run from the same PC and web browser.

All tests were run against using the same servers where possible; I highly recommend as it keeps track of your test history and presents the results in useful formats – including as a downloadable .csv file.

Test results can vary wildly, it is important to run multiple tests immediately before and after each change if you want to gain an idea of what sort of improvements you are seeing. The time of day, day of week and even the weather can affect results.


Since we have two ADSL connections at home (one Xtra, one Orcon) I ran a quick comparison with an Xtra account. Hardware is ADSL2+ capable D-Link DSL-502T. The connection appears to be 256kb/s up – so the download speed seems quite slow; ping times of 216ms for such a local connection are terrible.  The results are quite surprising and indicates that your choice of ISP may also be important, but bear in mind that the only known common factor is the distance to the exchange.



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