Bizarre Network Problem

[Bleak]

Now I'm half way through CCNA and hosted a few small LAN parties before so I do know a bit about networking already, but this problem I've just had with our home network I can't pinpoint an explanation for.

A Router linked to a hub with 7 other ports connected up, 3 of which are in use. A PC next to the hub is connected along with the PC in my room and one in my brother's, until...

My brothers GF's laptop, which has been on wireless all day is plugged into the 2nd wall port in his room, my PC instantly stops communicating with the network properly. There is physical connectivity because all the necessary lights are on the NIC and the hub. However, logical connectivity such as ping doesn't work.

I tried the 3 different network cards that are on my PC (2 onboard the mobo, 1 via PCI) and assigned different IP addresses, I tried different cables, I tried the other wall socket in my room, I get some long CAT5 out and try connecting through the 2 ports in my Dad's room. No success.

Following this I plug my laptop into the same cable I've been testing and hey presto, connects no problem. I then get my brothers GF's laptop unplugged from the network and my desktop PC connects again without any problems at all.

I believe it's the 2nd time this has happened now, apart from the 1st time it coincided with the CAT5 I was using suddenly not working so I wasn't entirely sure. This time round my Dad was on his PC and a couple of times it warned him that the network cable was unplugged, but it only lasted a few seconds and didn't have problems to the same extent as me. My brother's PC had no connection issues but whatever he was copying fluctuated between 100Mbps and under 10Mbps to the laptop.

Clearly it's a problem with the network card on the laptop because unplugging it solves all the issues, but could there be a problem with my PC as well? Why is it always picking on me!?!

Any thought or ideas will be greatly appreciated, hope this wasn't too long.

Bleak

[Pulseammo]

What happens if you plug your brother's GF's laptop into the wallport somewhere else? Does the problem still occur? What about moving your brother's wallport to a different port on the hub, does it still occur?

Perhaps there is faulty wiring inside the hub? Perhaps the hub has a forced connection limit in the firmware (I've seen stupid stuff done on home routers before like 4 PCs max including the wireless). Have you tried plugging any other PC or Laptop into the second wallport in your brother's room?

[Bleak]

Didn't try and move her laptop around because they were in the middle of copying stuff. She's also gone back home now because of work in the morning so further testing will be an issue.

Back in the day when our parents were on holiday we used to have LAN parties and all the ports got used up then and never had a problem. Faulty wiring inside the hub wouldn't explain why my laptop worked instead of my desktop PC through the same port though.

[smargh]

Flow control & duplex settings on each of the devices concerned?

What is the make & model of the switch & router? Is DHCP being used on all/some PCs? I know you tried different network interfaces, but do they all definitely have different MAC addresses (it has been known to happen...)?

Is there anything in your Windows/[otherOShere] event logs?

[note: i have a habit of missing things from initial forum posts... just tell me if i missed anything which makes the above questions stupid]

[Jay]

do you really mean hub or do you mean switch? If you do mean hub you may have collision issues.

[Bleak]

Flow control and duplex setting all on auto.

Router: Netgear DG834g
Hub: Ediman Palmtop Dual Speed Hub

DHCP is on the router and assigns addresses to all PCs. I didn't check the laptop that was plugged in but that's why I tried assigning different addresses myself anyway. The MAC addresses are different. I've also heard of them being the same on occasion but usually that's only the case if they're from the same manufacturer because the first half is assigned specifically to them. I was switching between the nForce onboard and a D-Link PCI card.

Yes it is a hub, about 7 years old and in the most part has been very reliable considering it's a bit cheap and cheerful. I really don't think it's collision issues though because the problem occurred before and after data was being transferred, but as soon as the cable was physically unplugged my desktop PC started working again.

[Jay]

what happend if you plug her into the routers switch and the rest of you into the hub?

[Paranoid2000]

What version of Windows is the wireless laptop running? If it is Windows Vista, then this has a network feature called "TCP auto-tuning" which can cause problems with some routers. To disable it, log in as an Administrator on your system, open a Command Prompt window and type the following:

netsh interface tcp set global autotuninglevel=disabled

You can check the status of auto tuning (on the line "Receive Window Auto-Tuning Level") with:

netsh interface tcp show global

and set it back to its default value with:

netsh interface tcp set global autotuninglevel=highlyrestricted