What's causing erratic wifi behaviour?

July 14, 2009 2:51 AM

What would make my laptop sporadically lose visibility of all wireless networks?

I have a Fujitsu-Siemens Amilo Pi 2515 laptop, running Vista Home Premium, which is behaving erratically wifi-wise. Very frequently it will stop detecting that there are any wireless networks around, and disconnect me if I'm connected at the time. It may then detect them again a minute or two later but then will usually lose them again shortly afterwards, and then the cycle continues. When connected it works perfectly, and it has no other problems. Even when not detecting the networks it will believe that everything is fine - it just can't find any networks.

This behaviour isn't predictable; sometimes it can stay in one state for an hour or so before changing. There doesn't seem to be any way to make it change - moving etc. doesn't really seem to do anything. Upgrading the drivers has had no effect, and I also tried booting from an Ubuntu live cd, which showed exactly the same symptoms.

What could be causing this inordinately frustrating weirdness? The only explanations I can think of are that either there's some loose connection internally (maybe to an antenna? do they have them?) or that the wireless component itself (an Intel 3945abg) is borked. As it's out of warranty both of these sound pretty expensive to fix; might I be best off just buying a wireless card to plug in to the expresscard slot? I'd like to be confident that it will work before spending that money.

posted by thoughtless to computers & internet (13 comments total)

Does one of the function keys double as a wireless on/off button or is there a separate button on the chassis for disabling and enabling wireless? It would have the little wireless antenna symbol on it. You might be accidentally hitting the key or button. I've seen this happen to a couple of people.
posted by ellenaim at 3:14 AM on July 14

It doesn't seem to be anything to do with the wireless switch - I've tried toggling it on and off, and even forcefully pressing it into the on position, and it has no effect on the behaviour.
posted by thoughtless at 3:18 AM on July 14

Is this only with your own wifi, or does it happen at other wifi spots? I.e. are you sure it's the laptop rather than the router?
posted by Electric Dragon at 4:00 AM on July 14

I'm practically 100% sure it's the laptop, ED - it happens whatever the network I'm trying to connect to. And when I'm at home, say, I can initially see the networks of neighbours as well as my own, and they all disappear at the same time as mine.
posted by thoughtless at 4:25 AM on July 14

I ask because I had a similar problem with my wifi a while back, but the laptop connected without problem to other networks. It turned out that there were too many other nearby routers on my street broadcasting on the same channel, so I changed the channel on the router and that cured the problem. There's a troubleshooting guide here - mainly for anyone reaching this thread in the future as it sounds like you've checked most of that.

If the driver updates aren't helping, are there any BIOS updates?
posted by Electric Dragon at 5:06 AM on July 14

It certainly sounds like the wifi card with those symptoms, especially losing access to multiple wifi networks at the same time.

It's pretty straightforward to check the aerial connections to the wifi card, and also swap it out if necessary. If it's like other fuji's, there should be a single large plate on the underside with a 'lift-up' slot, held down by a dozen small phillips screws. It may also have a small plate just for the wifi/memory.

Turn it off, disconnect the power supply and battery. Earth yourself (by briefly touching a radiator or other metal object connected to ground) Take off the plate.

You should see a small card like this (about half the size of a credit card) with two small wires going to the little clip on sockets at the top of the card.

You should be able to unscrew the two screws at the top of the card holding it down, and pull it up. Check the cables are firmly on the connectors - take the card out of the laptop entirely if necessary.

If the aerials are clipped on properly, and after checking it and screwing it all back together you still have the problem, it's probably worth just replacing it. You could replace it with an intel pro 4965agn, and just plug in to the far left and right aerial plugs. You could also get an intel 5300, which has 5Ghz 802.11n support as well as 2.4Ghz 802.11n support. Pretty much any mini-pcie wireless card will work though.
posted by ArkhanJG at 5:31 AM on July 14 [1 favorite]

Sorry, the plate underneath should be held down by a half-dozen screws or so.
posted by ArkhanJG at 5:33 AM on July 14

I had this problem bigtime when I first got my laptop. A few things improved the situation for me without popping open the machine;

Firstly to stop using the drivers that came with the laptop and to download the drivers from the wireless cards manufacturers site

Secondly to let the manufacturers app (again downloaded from their website) handle the wireless networking instead of Windows.

Thirdly heat seemed to be an issue. When the laptop got hotter the network connections frizzled so making efforts to keep the machine cool made a difference too. (Nowadays this seems to be the only thing that causes a problem so if I'm doing some big video crunching I lose networks.)
posted by merocet at 5:50 AM on July 14

Thanks for the advice, ArkhanJG - I'll check that out tonight.
posted by thoughtless at 5:56 AM on July 14

Try running a live linux distro - warlinux seams good for wifi debugging.

My money is on stupid windows vista drivers.
posted by lamby at 7:12 AM on July 14

Lamby: I tried Ubuntu, I assume this proves well enough that it's not Windows?

Merocet: as above, not just a Windows issue. I'm pretty sure it's hardware, and I don't think it's heat related as it's been in pretty well vented situations and not worked.

ArkhanJG: well, I opened it up last night, and all seemed well, except that the card had little black and white pointers to its aerial connections, and the black and white aerial leads were connected to their opposite-coloured connections. However, as it worked when I first bought it, I'm going to assume this isn't a problem.

Next stop: amazon, for a 5300; I figured I might as well, as there's very little difference in the price.
posted by thoughtless at 2:41 AM on July 15

It definitely sounds like the wifi card. If the aerial leads were damaged (broken in the hinge, say) you'd see an overall drop in signal strength all the time, not a strong signal then nothing at all. If it was drivers/software, it'd work in ubuntu, or at least be broken in a different way. If it was radio channel interference, it would work elsewhere, but not at home. If it was an issue with the router, it would always have done it at home, and worked elsewhere. So given you've investigated all that, that pretty much leaves loose aerial connection, and card fault. You've checked the first now, so that just leaves dodgy card...

Don't worry about the pointers; both aerials are the same, they're just in different aspects to give you better coverage. It generally doesn't matter which aerial sockets you use either, but
it's conventional to use the two outer plugs on a 3 aerial socket card.

With only two aerials, you may struggle to run dual-channel 5Ghz 802.11n speeds (i.e. 300Mb/s) but I'm guessing that's not going to be a problem right now, since you only had an 802.11g card in the first place and your router probably isn't even 802.11n at all. If you do ever want to use the 3rd aerial plug to improve signal strength/speed, you can buy an additional aerial (like these) and just stash it somewhere under the keyboard. It isn't required to get you going again now though.

Best of luck, and hope the new wifi card does the trick! Don't forget to download the drivers first, before you swap it out ;)
posted by ArkhanJG at 5:43 AM on July 15

Installed the new card this morning and everything works like a dream! Hard to be 100% sure with an intermittent problem but I reckon it's all sorted now. Thanks for all the advice, y'all.
posted by thoughtless at 1:48 AM on July 18