Internet speed very slow only in WiFi and in just one laptop

Question

I have Xfinity internet at home. All the devices (a couple of laptops, phones, tablets, etc) are connected via WiFi, except a PS3 which is connected via ethernet cable.

A few days ago we got the Xfinity gateway (router+modem) replaced because we had problem with it. I don't know if it's a coincidence, but around the same time I started to notice very slow internet in my work laptop. I've been doing speed tests in all the devices and they all seem fine (normal speeds) with the exception of this laptop (very slow speed).

I've been doing some tests:

1. If I connect the laptop to the router via ethernet cable, the internet speed is normal again.
2. If I boot the same laptop with Windows 8 (I have it with dual boot Windows 7 and Windows 8, but I usually use Windows 7), and do a speed test, the speed is normal again.
3. I've restarted the router/laptop several times and speed via WiFi still very slow
4. I've removed the WiFi network from the remembered networks of Win7 and connected to it again as if it was new network, and speed via WiFi still very slow

By slow speed I mean around 2Mbps when normally I would get around 35Mbps. The upload speed doesn't seem to be affected by this problem, it's usually 6-10Mbps.

Any ideas how I can get my laptop to get the same speed as always?

EDIT

So following the advice given in the first answer I reinstalled the drivers of the wireless card. I've been doing some tests with it and the rest of devices, and it seems that now I'm getting more speed that before, but the download speed still slower than expected. Although it fluctuates quite a bit, most of the results I get are around 10 Mbps, when before they used to be around 35 Mbps. Besides, it seems that in the rest of devices now it happens also the same (it's hard to tell because of how much the results change on each test). Can it be a hardware problem of the router/modem? Is there any way to test that? I called Comcast the other day and everything seemed fine on their end.

Solution 1

Because you mention that it works better in Windows 8, it could be a driver problem. Make sure you have up-to-date windows updates, including optional updates which sometimes have vendor specific hardware updates. Try locating your network adapter in your device manager, right clicking the adapter and select "Update driver software..." If this is already up to date, try uninstalling and reinstalling the driver. If this is a dongle and not internal card try searching for the driver directly from the manufacturer.

Solution 2

I'm sure you've already checked this but have you checked to verify that there are no energy saving settings enforced on the wireless card (selecting the battery icon in the lower-right hand side of the task bar and seeing if you're set to use a Balanced or Power Saver mode)? Being a work laptop I wouldn't be surprised if your IT department has configured by default Balanced or Power Saver battery plans. These can adversely affect your WI-FI performance. Furthermore, these would be different between operating systems.

Check this by searching for Power Options in the Start Menu and alternating between power plans as needed. I typically recommend High Performance to see if that resolves your issue. Power settings specifically related to your internal NIC can be found by selecting Change Plan Settings; Change Advanced Power Settings; and adjusting the Wireless Adapter Settings.

Comments

[Albert]

If that's the case, how do I solve it? It just happens in one laptop...

[Albert]

thank you, I'll try that as soon as I can. I have a question though: in my network devices I see Intel Centrino Wireless N-6150 and Realtek PCIe GBE Family Controller. I believe that my laptop uses the first one for wireless conection, do you know what's the second one? Is it the ethernet one?

[Bryan]

That is your onboard ethernet NIC (Network interface card).