Laptop brings down/swamps LAN

cplloyd · 30 Sep 2016

Hi,

I have a HP laptop that has developed the annoying habit of making our LAN extremely slow.

Using speedtest.net as a guide, I typically get 1.3Mbps download speeds with our 2x desktops (ethernet connected) and another laptop (WiFi connected). Our Internet connection here is via ADSL.

Every time I connect the 2nd laptop, either via ethernet cable or WiFi (using the built-in card, or a USB dongle), the speedtest.net utility almost (and sometimes does) grind to a halt. Disconnecting the laptop from the network whilst speedtest is struggling immediately returns it to its former speed.

The laptop (as is all the other PCs) is protected via Macafee Total Protection, fully maintained, and I have just run Malwarebytes Anti-Malware and have found no issues. It is running Windows 10 with auto update enabled.

If anyone has an idea for me to follow up, I would definitely appreciate it.

Paul.

PS Just to add confusion to this mix: I have just tried connecting to our ISP via their WiFi modem (their mobile network service) and I'm getting normal performance from speedtest.net - 2.5+ Mbps. What's up with the ADSL that our 3 other PCs are not suffering? (Note: with this test, the laptop is not connected to our LAN.)

PPS Even further confusion: After running the laptop with the mobile network service for about an hour, reconnecting to our LAN via WiFi has not caused the problem. I'll continue monitoring and advise of any further problems.

cplloyd · 01 Oct 2016

A further update:
1. The problem-free session lasted about 3 hours, before the Internet speed "crashed". We just had to disconnect the laptop if we needed to access the Internet. We switched off all PCs overnight (but kept the modem on and ADSL connected) and checked again this am - the problem was still there. We then switched everything off for an hour+ and connected only ADSL, problem laptop with WiFi - no problem found and it's been like this for the last 3 hours.
2. Checking our ISP's link statistics we find huge volumes of downloads - very much larger than we were actually downloading.
3. Whilst the problem existed I tried copying a 300MB file across our LAN to the problem laptop with and without the ADSL connected - there was essentially no real difference.

I'm starting to suspect that a Web site my wife was using to view tutorial videos might be a source of the Internet overload problem.

More test results to follow.

Paul.