Internet noticeably slower on one computer while faster on another connected to the same router

Question

I have a 120Mb/s Internet connection and it works well on my laptop with 1Gb/s network card and Windows 7. But it works too slow on another computer which is older and which have 100Mb/s network card and also Windows 7. Both computers are connected via wired Ethernet.

I realize that I won’t get the full 120Mb/s on a 100Mb/s network card, but as far as I know it should work with speed about 90Mb/s, but it is only getting about 35 Mb/s.

I am using Ubee EVW3226 modem/router device and I have updated network card drivers on the systems in question.

Solution

Few things to try (test your speed after each step to see if the problem persists):

• Connect the computer to the router using a different ethernet cable.
• If you have a switch in between the computer and the router, try connecting the computer directly to the router.

• Check link speed/duplex:

  1. Press Win + R to open the Run menu, and type devmgmt.msc to open Device Manager
  2. Expand Network adapters and double-click the appropriate adapter
  3. Navigate to the Advanced tab
  4. Select Link Speed & Duplex from the Property list and make sure its value is set to Auto Negotiation.

• Reset the TCP/IP stack¹:

  1. Click Start, search for cmd
  2. Right-click cmd.exe and click Run as administrator
  3. Type netsh int ip reset c:\resetlog.txt and hit Enter
  4. Reboot the computer.

¹You can also use the Fix it wizard from the following link: https://support.microsoft.com/en-us/kb/299357

A corruct TCP/IP stack can cause several issues with the network connection. Resetting the TCP/IP stack will overwrite the following registry keys:

SYSTEM\CurrentControlSet\Services\Tcpip\Parameters 
SYSTEM\CurrentControlSet\Services\DHCP\Parameters

This has the same effect as removing and reinstalling TCP/IP (https://support.microsoft.com/en-us/kb/299357).

If none of the above solves the problem, your network adapter may be bad, or you could have some sort of malware which is hogging the bandwidth.

Comments

[Giacomo1968]

Are both computers connected via wired Ethernet or Wi-Fi? I assume this is wired Ethernet from the description of the speeds in your question but want to confirm.

[barlop]

coyld try a live OS like bart pe or a linux one

[ctomek]

@JakeGould Yes, both are connected via wired Ethernet. I'll add this info to my question.

[ctomek]

@barlop I'll try that soon, but right now I can't.

[Ecnerwal]

Some ethernet adapters have trouble actually moving data as fast as they claim to - though this was more of a problem with 1 Gbit adapters (lighting the Gb light, but not being able to fill the link) than 100 Mbit adapters, as far as I recall.

[user]

This would be better if you explain a little (doesn't have to be an essay) about what resetting the TCP/IP stack does. Generally speaking, don't encourage people to do things blindly, especially when the implications are non-obvious (I've been using IBM compatibles since the late 1980s, and I don't know what resetting the TCP/IP stack on Windows will do); explain why you believe that particular step is relevant to solving the problem described by the OP, and say something about what the potential pitfalls might be.