Why Do My Download Speeds Differ So Drastically Between Computers? – Lifehacker Australia

In a perfect world, youd pay for super-fast internet service, connect your cable modem to a reasonably speedy router and realise incredible download speeds for every device in your home. Unfortunately, we live in the real world, which often paints a much different picture.
In the real world, you overpay for data-capped unlimited internet service and end up renting a cable modem from your ISP for even more money. Its a router/modem hybrid that gives you a so-so connection for your many devices throughout well, part of your house. You ponder what it will take to get a wireless connection to cover the dead spots and end up buying a crappy extender that helps you achieve a fraction of the speeds youre paying for. You wonder why this is so complicated.
Lifehacker reader Jon might not have quite as bad of a setup as this, but his question for this weeks Q&A reminds me we live in a world in which a regular person has to jump through a hell of a lot of hoops to (maybe) set up a speedy internet connection. He writes:
I have 2 PCs connected to the same new, managed Netgear switch. All my gear is 1000Gbps capable. As an example, here are two screenshots of speedtests I ran on both PCs: first PC1, and then PC2.
Im not understanding the huge speed difference between testing on same subnet via same router/cable modem?
PC #1 transfer speeds:
PC #2 transfer speeds:
Jon actually sent me a lot more detail about the various things hes already looked into in order to max out the connection speeds on his 1Gbps internet plan. (Its a lot! Two cable modems, two mesh systems, lots of Ethernet and coaxial cable. A lightning strike. Its quite a story.) For the sake of brevity, however, this is his problem at its root: inconsistent performance, even on a wired connection.
At least, Im assuming wired. Lets just get that out of the way first: If PC #1 is connected via Ethernet and PC #2 is connected via a wireless card, thats your problem right there. Its a lot trickier to get a consistent, incredibly fast signal over Wi-Fi theres a lot that can affect the quality of your connection and the resulting speeds, something Ive addressed in numerous columns.
Its also possible that the speed test is reporting different results simply because they do. However, its strange to see such wildly different results from the same speed test accessing the same theoretical testing location. I presume youve run the test quite a few times and seen consistently large differences in performance between your two PCs.
What I might do first is try a few other speed tests in case theres some kind of aberration with Speedtest. Ive always liked using fast.com, but there are plenty of others. You want to determine if youre seeing the same crazy variance between your two systems across multiple tests. If so, we can start to narrow down our troubleshooting to something potentially related to the ailing system. If not, or if the results invert, then youll probably want to take a step back and consider some general troubleshooting (or just dealing with the odd variances).
For the sake of argument, lets assume that your various tests indicate that PC #2 is still slower than PC #1. Theres a lot we can do to try to fix that, so lets dig right in.
Start by swapping the Ethernet cables the two PCs use or connecting via another new, cheap Cat 6 cable. Perhaps the network cable youre using on your slower PC is having an issue. It could also be rated too low for the distance youre using it (and the speeds youre hoping to achieve). You might even have a loose connection of some sort. Try a different cable. Run your tests. See what happens.
I presume that PC #1 and PC #2 are both connected to your router the same way. If PC #1 has a direct Ethernet connection but PC #2 is connected to a powerline adaptor, which is how you manage to give it an internet connection without stringing Ethernet cable all around your home, thats probably where the bottleneck is. When youre running your tests, make sure youre connecting directly from router to desktop.
Dont forget to reset everything on your network before running your speed tests. Reset your modem, your router, your PCs and any other devices between the two even power cycle any switches youre using as part of your network, (something that Ive had to do to get my Ethernet-connected desktop PCs speeds back up again.) Yes, switches are generally dumb, but they can act up sometimes.
If this hasnt fixed the issue, dig deeper. Try connecting your Ethernet cable(s) to different ports on your switches or router. Does PC #2 have a second Ethernet port you can use? Try that and see what happens. Theres not much else I can think of as far as hardware goes unless youre using some kind of discrete networking card or USB adaptor to get an internet connection on PC #2, which could also be your point of failure.
On the software side of things, check to see whether there are any firmware updates you can install on your modem, router, switches or motherboard to name a few. Its possible theres an update that has fixed a defect thats otherwise costing you speed. Its also possible that one setting or another has malfunctioned, and flashing updated firmware (which typically reverts your settings to factory default) can help fix that.
Otherwise, consider resetting your modem to its defaults, then your router, then possibly even your BIOS and/or operating system. Yes, its the wipe everything and reinstall approach, an option Id recommend as a last resort, but one thats always on the table for you to try. (Are there any strange networking-themed apps on your system that you dont recognise or dont use? Uninstalling them might help.)
Check to see if your PCs (or your network interfaces) manufacturers have provided any updated drivers you can install. While Im not convinced thats what is causing your slowdowns on your second PC, its an easy fix to explore. While youre at it, update the DNS settings on PC #2 to something speedier (like Google DNS or Cloudflare) instead of whatever youre getting from your ISP.
You can also try resetting your TCP/IP stack by opening up a Command Prompt as an administrator and entering the following:
netsh int ip reset
I wouldnt suggest buying anything new until youve exhausted all your troubleshooting options. If you happen to have a friend with an Ethernet adaptor you can use, see if that improves your speeds at all. A cheap PCI-based or USB-based one is fine, though I always prefer the former, as it offers less potential for complications. (Thankfully, if you have to buy one, a decent gigabit card can be had for less than $30 a small price to pay to double your internet speeds.)
Thats all I can think of, though. Hopefully one of these techniques will solve your tricky issue. Even if they dont, though, 400Mbps on one system isnt too shabby. I know its not the 700+ Mbps you were hoping for, but youll only really notice the slowdown when youre downloading huge files. Otherwise, if theres any silver lining to be found in this problem, I would expect that latency (and DNS) will impact your typical web browsing experience more than this speed difference.
Do you have a tech question keeping you up at night? Tired of troubleshooting your Windows or Mac? Looking for advice on apps, browser extensions, or utilities to accomplish a particular task? Let us know! Tell us in the comments below or email[email protected].

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