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[FrostySonic]

Hi all,

I recently purchased an DIR-655 here in Australia (A3, running Australian-dlink approved 1.21), and in doing speed tests i've noticed some weird behaviour:

I'm on 8000/128 cable internet and can usually download at up to 1200KB/s.

After installing the router I noticed my download speed topped out at around 500KB/s, and testing it without the router it downloaded at the usual 1200KB/s.

So I went through nearly every setting on the router to see what was limiting the speeds, and eventually discovered that under "WAN Traffic Shaping" in the QoS settings in the section, that the "uplink speed" setting was limiting the download speeds.

The router had automatically measured my uplink speed at 130kb/s (pretty much correct). However if I manually increased the uplink speed, I noticed that the download speed through the router also increased.

Once I had increased the uplink speed setting to around 1000kb/s, my download speed pretty much maxxed out at the usual 1200KB/s.

So that's how i've got it set for the time-being, but I have a feeling that keeping the uplink speed set artificially high won't have to QoS engine working like it should.

But still, has anyone else experienced this, and why the heck would the uplink speed setting have any effect on the speed of downloads?

[Demonized]

You have an 8 Mbit downstream connection? According to the Great Book that will get you a max download speed of 800-880 Kb/s. Either your ISP has provided you with extra bandwidth OR the speedtests aren't correct.

[FrostySonic]

yeah, that's pretty much right. "Officially" it's 8mbit, but in practice i can get 1200kilobytes/s. I can get those type of speeds both in speedtests and downloading from capable servers like the akamai ones in the region.

[Demonized]

QoS manages the upstream data traffic, but does not interfere with downstream traffic.
There is a possibility that you have some other clients generating upstream traffic which is influenced by the bandwidth setting.

When upstream bandwidth is small or congested, this will influence downstream speed as well, since TCPIP depends on send-receive two way communication. If the 'question' (send upstream) is delayed, you will not get a swift answer (receive downstream)

[FrostySonic]

that does make sense, But I only have a small network here (2 PCs and 2 games consoles), and at that time the only client that was powered on was the PC I was doing the speed tests on (of course at the time I wasn't torrenting or downloading anything else).

I did multiple kinds of speedtests (speedtest.net from various locations, ozspeedtest.com (which has a flash as well as a javascript testing base), as well as plain file downloads from one of my ISPs linux distro mirrors), and all reported roughly the same ceiling in terms of the speed.

I guess what i'm saying is that in doing all the tests, the QoS at the time should have had almost all of the available upstream bandwidth to work with.

[lizzi555]

If you use XP, you may try the TCP Optimizer here:

http://www.speedguide.net/downloads.php

Sometimes it worked wonder 

Also try what happens if you deactivate QoS complete.

[FrostySonic]

Actually, if i deactivate QoS (by unticking the "Enable QoS Engine" option), the speed is still capped at ~500KB/s.

It seems that it really is the "WAN Traffic Shaping" section. If I untick the "Enable Traffic Shaping" (the section where you set the upstream speed), the issue isn't present.

Still, I can't see why it would be affecting the downstream speed by that much. I mean we aren't talking a small margin, it's effectively reducing my downstream bandwidth by 50%.

[lizzi555]

As traffic shaping generates data packets in different sizes in order to optimize extent of utilization, it may not be fully compatible with your provider.

Perhaps you better leave it disabled.

[tentimes]

I posted about this very issue a while back. Make sure you manually set the uplink as if you don't it does read wrong quite often and that will strangle your downlink. I keep QOS on but always set my uplink maanually.

I wish someone would sticky this as it is a known issue and cannot be fixed, plus I would imagine it happens a lot.

[GVG]

I have the same issue. I have a 20/512 connection, but if I let the QOS determine the speed by itself my download throttles to about 8mb. If I fake the unit out and tell it my upload is 3072k, then I get my full 20mb down. I called tech support at DLink about this and they did not even understand what I was talking about and were completely clueless as to what the StreamEngine QOS in the router was.  In fact one person insisted that the QOS only worked on the downstream and had nothing to do with the upstream. I tried to explain to him he had it backwards but he just could not understand.  Of course all of the people I spoke to were in India, so my chances of getting someone who really knew the product, much less ever even touched one were pretty nill.

So I keep it faked out, I have my full speed and the QOS seems to be working well. My VOIP calls all sound good.

[FrostySonic]

I posted about this very issue a while back. Make sure you manually set the uplink as if you don't it does read wrong quite often and that will strangle your downlink. I keep QOS on but always set my uplink maanually.

I wish someone would sticky this as it is a known issue and cannot be fixed, plus I would imagine it happens a lot.

I don't mind setting it manually, but I do mind having to set a totally incorrect value in order for the download speed to be what it should.

Why can't it be fixed? Surely it's a firmware issue and not a hardware one?

It's good to see i'm not alone though. I might email support and see if I can get a further response out of them...