Ethernet speed mystery

I get unusably slow network speeds on my HP 8530W laptop when connected via Ethernet. Here are the results of some unscientific tests, comparing throughput reported by Windows while copying a 130MB file from a local server, Wifi vs Ethernet and this laptop vs a similar Dell laptop in the same room.

HP 8530W (WiFi) 1.9 MB/sec
HP 8530W (Ethernet) .0046 MB/sec (4.6 KB/sec)
Dell (Wifi) 1.5 MB/sec
Dell (Ethernet) 12.2 MB/sec

HP has sent out a technician to replace the Ethernet adapter, which involves replacing the entire motherboard, twice, with no improvement. So I'm pretty sure it's not the hardware.

In the tests above, both the Dell and the HP are using the same physical cable, same hub. So I'm pretty sure it's not the network.

That only leaves software. But this was happening before I did a clean install of Windows 7, and it's still happening. The laptop is running the latest BIOS, and the latest drivers for the Ethernet adapter.

So what could the problem possibly be?

Herb Caudill

Posted 2010-01-27T22:20:40.450

Reputation: 879

does network speed change or stay the same when you use a Linux LiveCD? – quack quixote – 2010-01-27T22:41:52.570

Just to clarify, by "same physical cable, same hub" you mean that you're moving the cable back and forth between the HP and the Dell, right? – rob – 2010-01-27T22:46:53.387

@rob - Right, moving the same cable back and forth. – Herb Caudill – 2010-01-27T23:01:59.857

Answers

Thanks for the good answers. Further investigation revealed that the switch in my office was the problem. I could connect my ethernet cable directly to the wall and get normal 12MBPS throughput. The switch was a garden-variety Linksys EZXS55W, and I happened to have another one lying around; when I swapped them out, the problem went away.

So strange that the Dell didn't have any trouble with the "bad" switch, though.

Herb Caudill

Posted 2010-01-27T22:20:40.450

Reputation: 879

Just a stab in the dark, but the Dell might use a different ethernet controller than the HP? This can result in different behavior in relation to networking equipment. – Scott – 2010-01-27T23:48:53.773

@marcusw - I will, but can't until 48 hours after posting. – Herb Caudill – 2010-01-28T11:58:27.653

It could easily be a crappy driver for the HPs NIC that is causing the problem. Check HPs site for an updated (or older) driver and see if that helps. If it doesn't you are pretty much stuck until they release a drive that doesn't have the problem.

Also are you sure that you are connecting at 100 Full (or 1000 Full) and not 10 Half on the link speed? Try hard setting the link speed to the fastest that the hub supports.

mrdenny

Posted 2010-01-27T22:20:40.450

Reputation: 574

First I'd check for signs of damage to the cable, and try a different known good cable even if there aren't any visible signs of damage. Maybe it's damaged in such a way that it makes a good connection to the Dell, but not to the HP.

Second, I'd make sure there aren't any potential sources of interference near the network cable when it's hooked up to the HP, such as an UPS or other high-voltage or high-current device. Maybe it would be beneficial to physically move the HP to a slightly different location.

rob

Posted 2010-01-27T22:20:40.450

Reputation: 13 188

I experienced a bit of this on Vista 64-bit, but not so drastic. It was sending me back to 100Mbit speeds instead of the 1000Mbit it should have been on.

In the end I went to Control Panel > Programs and Features > Turn Windows features on or off and disabled the Remote Differential Compression option.

After a reboot my speeds were closer to what I thought they should be.

Good luck!

Steiv

Posted 2010-01-27T22:20:40.450

Reputation: 478