Internet becomes very slow when laptop charger is plugged?

September 5, 2014 at 10:04:22
Specs: irrelevant (tried live distros like linux and ubuntu, nothing), irrelevant
2 months ago I bought a Dell Latitude E6400 for my little sister and everything was perfect.

It's been more than a week now since whenever she plugs the laptop battery charger, internet speed either drops to 10%-5% of the original speed or just stops completely, both on my desktop pc and her laptop. Whenever it's unplugged and the laptop runs on battery, speed goes back to normal. (both computers are connected to the modem via ethernet cable).

I've tried all possible power source sockets around the house, as well as changing the modem power adapter, no changes. I've checked all possible settings related to this on both computers and modem, nothing relevant. I asked a friend to bring his laptop and it worked fine plugged/unplugged. The only thing left is to either replace the battery charger (I removed the battery and booted the laptop with the power adapter only, didn't make a difference) or buy her a new laptop, but I don't really want to do that unless it's necessary. So did I miss something or my house's electricity sockets doesn't like laptops anymore? Like really, what's going on


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#1
September 5, 2014 at 17:04:46
Most weird. It would be interesting to know:

1. Does this still happen if you take the Ethernet cable out of the laptop?

2. With the Ethernet cable in place does it happen if you disable Ethernet in the Control Panel?

Always pop back and let us know the outcome - thanks


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#2
September 5, 2014 at 19:21:48
Are there any automatic updates configured on the laptop?
Or any software that starts running when the laptop is in charging mode?

Seems the laptop starts downloading something when on AC.


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#3
September 5, 2014 at 22:43:26
Thank you for replying.

@Derek

1. No, internet speed is normal on my desktop pc when the cable is plugged off either the laptop socket or the modem.
2. When disabling the connection from the laptop in Control Panel, with the cable still in place, the speed is still reduced.

Strangely enough this morning I tried using Internet Explorer instead of Chrome and now I get around 1.5 - 2Mbps out of my 20Mbps connection (tests on speedtest.net), with chrome I get the around 0.6Mbps as usual or just connection error message from the website. What's more strange is that upload speed is working at full capacity (with IE), just the download speed is getting slowed down this time.

@sluc

No, I've disabled automatic updates for anything except Adobe Flash Player, which is up to date. No software runs when the power adapter is plugged, other than then Power Plan thing from Windows, adjusting screen luminosity etc.

I've also installed a network monitor program just to be sure and nothing strange happens with download/upload speeds the moment when AC adapter is plugged.

message edited by alxv1


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Related Solutions

#4
September 6, 2014 at 09:06:15
The symptoms are very odd. Better do a "quick check" for malware:

Install, Update and Run MalwareBytes from green button top right:
http://filehippo.com/download_malwa...
If it finds anything at all please copy/paste the log on here.

Download and "Save" the ADWCleaner file from blue download button near the top:
http://www.bleepingcomputer.com/dow...
Find the downloaded file and double click it. Run just the Scan only then paste that log on here too.

Always pop back and let us know the outcome - thanks


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#5
September 6, 2014 at 10:28:22
As I mentioned in the "Specs" section, I tried live distros such as Ubuntu and the problem is still there, so even if there was an undetected malware on the laptop I don't think it's the cause of the problem.

I'm starting to think the hardware is at fault, the PSU maybe, something is causing faulty management when it comes to the power adapter and the internet, but they're all theories at this point and I'm no electrician to it up and see if everything works correctly.

I've looked around some more and apparently there are a few people who had this problem as well, all with no solution. For now I told my sister to use the internet only when it's on battery but since she always play games or watch videos/movies it won't last long.

I'll update the thread as soon as something new happens.


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#6
September 6, 2014 at 10:39:01
Sorry, didn't interpret your specs as part of the reported issue.

If it does the same on a Live Linux distro CDE/DVD then it must be hardware. PSU maybe but it's real hard to imagine what it is doing. I'm more inclined to suspect the Ethernet card or module.

Always pop back and let us know the outcome - thanks

message edited by Derek


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#7
September 6, 2014 at 21:21:46
If you disconnect the cable problem disappears. Correct?
Other port on the switch or other Ethernet cable? Same problem?
Is the Ethernet port connected to the laptop blinking erratic even if nothing is downloaded?

No WiFi possibility between laptop and router?
Just to eliminate LAN-port problem of the laptop

In the Task Manager Network tab. Any (high) Ethernet traffic difference when charger plugged in

message edited by sluc


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#8
September 6, 2014 at 22:37:44
@Derek Yes, I was thinking the same thing.

@sluc Correct, if cable is not plugged either in the modem or laptop, speed is normal.

The modem port connected to the laptop is blinking as usual, static when no network activity, erratic when accessing the web.

It's a modem so it does not have any WiFi capability. That might be a good idea actually, I'll see if I find someone who can lend me a router just to test it, I'll let you know the results.

message edited by alxv1


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#9
November 11, 2014 at 02:40:18
Im having the same issue. I have a wireless router and regardless whether im using wifi or ethernet, if the power cord is plugged in, the speed drops to 1mbps...Not sure what to do

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#10
November 11, 2014 at 06:55:59
Hersh

Computers are different and no two issues are ever exactly the same. Please raise a new post of your own.

This will put your query at the top of the pile too (this one started on September 5th so few people will look at it now).

Always pop back and let us know the outcome - thanks


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#11
January 14, 2015 at 09:22:07
@alxv1
hi,
I have the same problem, and I think the charger is fried. I am saying that because when I use my brothers charger from an DELL Inspiron N5110 (I have a DELL Latitude E6400) everything works fine. Also when I use the charger from my latitude the battery is not charging.
Borrow another charger from a DELL laptop that is compatible with your sisters laptop and see what happens.
Let me know if this helps

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#12
February 21, 2015 at 20:19:45
So this is a power problem. The charger cannot supply the watts necessary to run the motherboard/CPU at full speed so it drops to lowest possible speed. The laptop probably charges the battery really really slowly as well. You need a new charger. And you can also change the setting in BIOS to alert you to a low functioning charger. But you will need a new power brick/cable.

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