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So, I've been sort of confusing myself with this question: Does your internet speed vary based on the distance from your router?

Immediately, I thought yes, of course it should! But then I thought, everything's being downloaded to your router, so if I do a speed test at speedtest.net, it shouldn't matter where I am. I confirmed this by doing a test on ethernet; right next to my router and then further away. They were all the same.

But, my friend did this with thicker walls in his apartment and he is getting different results from tests; they're getting slower the further away he goes from his router.

I can't seem to understand this. It sort of makes sense, but it doesn't make sense to me when I think more about it. I don't seem to get why this would be the case? I understand local traffic may take longer, but why not a speed test?

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3 Answers 3

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Your internet speed is independent of your Wifi strength. Your Wifi strength may affect the internet speed you see.

Sounds contradictory but let me explain. We're going to assume for this example your internet speed is 20 Mb/s, and your Wifi link is using the 802.11g standard, which can handle up to 54 Mb/s.

The first line - Your internet speed is independent of your Wifi strength can be explained by saying that no matter what your Wifi link is, your router is obtaining that 20 Mb/s. The question only becomes, can I get that speed to my computer.

Now for the second line - Your Wifi strength may affect the internet speed you see. is because Wifi is how you're getting the information to the computer. As you move further away from the router the signal between it and your computer degrades. When you're sitting right next to it, you may get the full 54 Mb/s bandwidth. If you move down the hallway you may get 40 Mb/s. If you go down the hallway into another room with thick walls you may get 25 Mb/s. The distance and amount of obstruction can effect the signal strength you receive.

So what does this mean? It means that if you have the capacity for an internet speed of 20 Mb/s, as long as your Wifi is able to produce at least this bandwidth or above, and no one else is using the bandwidth, you'll not notice a difference in your internet speed regardless of strength. You could be at 20 Mb/s, 30 Mb/s, 40 Mb/s - it doesn't matter because your internet can only put through a maximum of 20 Mb/s.

On the other hand if your signal begins to get really poor you might drop down to having a wireless link of 11 Mb/s. Suddenly as far as you'll see, you have a speed of 11 Mb/s. The internet connect itself hasn't slowed, but the maximum amount of it that's being passed to you has been reduced. Hence your Wifi can affect the (perceived) internet speed.

TL;DR - Vast majority of the time the internet is the bottleneck in speed, so varying signal strengths for Wifi don't matter. If your Wifi link degraded so much that it was a lower speed than your internet was capable of, yes you'd notice a slow down.

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Thanks for your explanation :) –  Prash Feb 25 '13 at 16:46

yes and no. wifi speed depends on distance from the wifi router. Internet speed does not.

Your distance from the wiki router does not affect the speed your router can technically get data from the internet, but as it is unable to shovel the data off to you via wifi as its slower, hence you see a slower download.

wifi actually uses speed steps, so it'll jump down to the next known speed if the current one isn't keeping a good link up. faster speeds need a better signal. It'll keep stepping down the speed until the link is good. Typical steps for 802.11g are 54Mbps, 36 Mbps, 24MBps, (then 11Mbps, i think). If your internet line is say 100Mbps - which isn't unheard of, you'll never speed test it correctly over a 802.11g wifi link.

There's exceptions to this (like most things). You can force your router to only allow certain speeds (dropping the connection entirely if it can't be reached) etc.

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I see. But I still don't understand why this would affect a speed test? Like, a speed test is to your connection (i.e. router), how would it know the "LAN speed" from your router to computer? I don't understand why it would show a decreased value. –  Prash Feb 25 '13 at 1:14
2  
To put it another way; If you send a letter to another country and it takes a day for the post man to take it from the postbox and put it on a super fast mail delivery aircraft, it still takes at least a day to deliver it. Your speed test is not testing your router->internet speed. It's testing the connection speed. That means all links of the connection, including your wifi. If you use a cable and plug directly into the router (most home routers allow this), you'll likely get a more realistic speed for the internet link because you won't have an artificial bottleneck in the test. –  Sirex Feb 25 '13 at 1:18

The link between the router and your PC depends, roughly speaking, by the signal-to-noise ratio. The stronger the signal (and the lower the noise), the higher frequency modulation can be adopted, and the more bandwidth becomes available.

Most WiFi routers/access points will try to maintain the highest data rate they can, even if this causes errors and renegotiations, which means that you just might squeeze more bandwidth out of a continuous 54 Mbps connection than from a shaky 104 Mbps or 300 Mbps connection that can't stay up. That is why sometimes lowering the top speed of the connection results in an overall improvement in data transfer rates.

In the speed test, the data is not downloaded to your router, but rather the packets get routed from the server to your PC, and the speed test server waits for your PC to respond. So, the total speed is the speed of the slowest component in this turnabout.

Exxaggerating the times, you get:

Server --- 1 ms --> Router --- 20 ms --> Your PC
Server <-- 1 ms --- Router <-- 20 ms --- Your PC

So the server "sees" the answer to its packets after 1+20+20+1 = 42 ms, and this is the speed it has to report, even if cable speed is twenty times higher.

If you had a proxy installed near your router

Server --- 1 ms --> Router --- Proxy --- Access Point --> 20 ms --> Your PC
Server <-- 1 ms <-- Router --- Proxy

then in some configurations (not all!), if a realtime answer from your PC is not necessary, as in most HTTP calls, then the server would "see" a lag of 2 ms only. You would still see your data after the usual 21 ms delay, though.

Applications that require an answer from your PC and no other, such as most online games, would still be affected by the WiFi lag.

For the same reason, "speed pings" to your router made from outside (e.g. from your ISP) would report a fast line: and indeed, the line they see - the 1ms trait - is fast.

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