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I have read : Windows 8.1 update effectively disabled wireless networking It didn't help.

I have just recently bought a Lenovo M5400 laptop and installed Windows 8.1 x64. According to the support website, the wireless card is : Cbt BCM943142HM 1x1BGN+BT4.0 HMC wlan

I've had multiple problems with my wireless internet connection since I installed it using the drivers on the support webpage. They gave me two drivers for Win 8.1 x64 for this card and I installed both of them separately to test it out.

Currently the device manager show me two possible drivers to use : - 1x1 11b/g/n Wireless LAN PCI Express Half Mini Card Adapter (which I assume is the generic Windows driver for this card) - Broadcom 802.11n Network Adapter

The wireless AP is a TP-LINK Wireless Lite N Router WR741ND that runs in bgn mixed mode on 40Hz channel width. I sit relatively close to it and have full signal. I've also checked and there is no interference on the channel.

The symptoms are as follow :

  • After a while of watching a video on YT for example the icon for the connection shows that I have limited connectivity.
  • While I have limited connectivity I can run the windows troubleshooter and it resets the adapter and the connection works again for a limited period of time.
  • When there is connectivity, using the ping tool there are relatively short periods when there are lag spikes. However the lag spikes don't seem to influence the limited connectivity problem since the episodes are separate.

I also have a PC that is connected with a cable to the router and another laptop that also uses a wireless connection to the same router. They do not show the same symptoms.

There is an extensive thread here but the technical support from Microsoft on this issue is less than helpful. I've also tried contacting Microsoft Technical Assistance but they only seem to prefer to talk via telephone and I'm uncomfortable doing that. I really don't know why Microsoft even offers the option of live chat.

Any help would be greatly appreciated.

On an off note : I've had a similar problem with another laptop while using Windows 7 and a Qualcomm card. The issue was solved by using an unofficial driver I found on a Czech webpage. Sadly I can't find one for this card.

Later edit : Nothing worked. Installed Windows 7 and it worked perfectly.

Later later edit : It did not work perfectly. The same thing kept happening just at less frequent intervals. I bought a new Intel wireless card and plugged it in but the BIOS guard kicked in and it didn't let me boot up.

It seems you cannot put a wireless card that's not signed by Lenovo. Which sucks and no one told me about it but apparently it's due to some sort of FCC regulation (figures as much, I didn't know that the country that I live in is subject to US commercial regulation and law).

Now I've lost the warranty since I opened my laptop to change the wireless card. This doesn't matter as much since it was "working as intended" if you can call it that. There seems to be a way to crack it by writing the ID of the old card on the new one but it's quite dangerous since even the smallest mistake can burn either the motherboard or the card and I'm not willing to risk it since this Lenovo Essentials M5400 laptop is one that Lenovo considers garbage-tier but in my country is worth about a two month salary for regular people. (long sentence is long)

I have fixed this problem by disabling the original card and using an external USB wireless card. Hooray for bad design and bad hardware. Lenovo went from respected brand to canned malarkey producers in my book.

I wrote this in case anyone wants to buy this particular model. If you're thinking of buying it, just don't. I have nothing to say about other models.

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  • For the lag spikes, go into the advanced driver properties and see if disabling power save mode makes the lag spikes go away. If it does, leave it disabled and see if it makes all your problems go away.
    – Spiff
    Mar 4, 2014 at 2:56
  • I will try it when I get home from work. Thank you for the suggestion. Mar 4, 2014 at 6:18
  • It is sad to say, Win8.1 + Broadcom = many bugs, you can see many "victim" when searching Google, btw you may need to try different kinds of driver version.
    – Bilo
    Jun 26, 2015 at 16:17

5 Answers 5

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I got my mother-in law to buy a Lenovo G510 and that computer had this network adapter too. I too had issues with the network losing connection and being unstable. I just found that the mouse that was included with the laptop was interfering with the network adapter.

If I use a different mouse or just the touchpad on the laptop, it is actually quite stable!

I hope you find the solution to you problem aswell.

Take care!

/Jakob

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  • Thank you for your answer. I've tried it but it didn't help. The same thing happens regardless of which device I use. Jun 6, 2014 at 18:37
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Same problem with Windows 8, worse with 8.1. Wireless Broadcom BCM9413HMG2L card. After days wasted messing with drivers and various settings, looks like disabling WMM on the adapter settings has stabilised the connection. Connection now maxes at 54 instead of N rates, but at least it is usable

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    Although there is something of an answer please clean it up and refine it to read more like an answer and less like a comment May 17, 2014 at 18:07
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Had this problem countless times with my Broadcom cards. It basically has poor support for non-Broadcom routers because of driver bugs. My 802.11n card works well only if i have one of them:

  • I use a broadcom-based router.
  • I use a version 5 driver. Latest is 5.100.82.147 (probably best idea)
  • Disable WMM (this limits speed to 54mbps)

My 802.11ac card works fine if i disable the "n" part or disable WMM. The driver available for "ac" cards start with version 6, which coincidentally messes up the "n WMM".

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I has a same problem (windows 8.1, broadcom wifi in laptop), pinging the router I got times around 10ms right after reboot, then over a course of cca minute it deteriorated to 400-800ms + timeouts.

I tried all drivers I found, no improvement. Then I read advice to disable WMM in driver properties. Didn't work. After that it ocurred to me to try diabling WMM on router.

Bingo - 1ms pings again, network runs greatly!

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For future reference, you didn't void the warranty. They might say it, but that is actually illegal. I came to this site because I'm having issues with my mini-adapter in my Lenovo desktop. But I wanted to let you know that you shouldn't be taken. Companies CANNOT void warranties because you open or try to repair the product.

I'm still looking for answers on why my adapter is pretty poor right now.

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