Wireless lan problem.

[Fossaw]

When we moved house, my machines were sent to a spare bedroom, rather than the dining room. The net router was downstairs, so clearly inconvenient for wired lan. I bought some TrendNet wireless adaptors, (Wireless N PCI Adaptor modules), fitted them, switched on and all seemed fine.

A few hours later, there was no connection. The router looked normal, my wifes laptop worked fine, but my machines were incomunicado. Rebooted and it seemed to fix things - for a couple of hours.

This was a year ago. I have been dogged by this problem since then. TrendNet say the problem is everywhere but with their cards. My wifes laptop if sitting on my desk upstairs, has no troubles. One of my machines has been upped to Windows 8, but the problem has not changed at all, (the others have XP).

I am about to bin these cards, but thought it might be worth asking here. What could be wrong, can I fix it?

[gemera]

Sounds as if the signal strength is just on the tipping point between reception and non-reception. Walls and ceilings can really attenuate the signal, whereas windows are pretty transparent to it. So if the spare bedroom window isn't orientated well to the downstairs dining room window I think your current situation would be pretty well expected.

[Fossaw]

... yet my wifes laptop has never had a problem, and has smaller antenna. This is a modern house, the walls are pretty flimsy affairs. As to the arrangement of windows, the dining room window is on the west side of the house, the bedroom window on the east.

Crazy thing is the signal strength meter always shows quite good, even when there is no connection. It is a bar chart like thing with 5 vertical bars of increasing height. Even when there is "no connection" it shows 4 greens. I only ever see it red or yellow during reboots.

[grumpy]

You need to check both signal strength and signal to noise ratio (SNR). Signal strength can fall due to geometry (i.e. as you move around the house, affected by shape and relative orientation of antennas not just size) and SNR can fall due to interfering sources (say, a neighbour's Wifi or some other RF source turning on and off - which would explain the intermittent behaviour).

A signal strength meter doesn't necessarily report just YOUR signal level. It can also report the total level due to your signal and interfering sources in the relevant bands. Interfering sources, by definition, reduce your SNR. In other words, you can appear to have a good signal level but lose out due to SNR levels.

Check what WiFi channels are being used. A lot of Wifi routers default to using the same channel (even from different vendors) and need to be specifically configured to use different channels to avoid interference. Some routers do have a mode of picking an optimal (least interference) channel, but not all do that particularly well. Most (non-router) devices scan, but it doesn't hurt to look up what settings they use for searching (some are configured to a particular channel).

It's possible the wife's laptop (on your desk) is sitting in a sweet spot. Or that its wireless is leaking between channels, and causing interference for other devices.

The other thing to check is the power setting for all of your devices. If one is not putting out enough power it (or devices communicating with it) may have trouble. Power saving features typically affect that, if enabled.

[Fossaw]

Vis signal strength - there is an icon in the tray which I've always assumed to be an indicator of signal strength. It normally shows 3 of the four bars lit, and floating the pointer over the icon, says signal strength is "Good". When the connection fails, this drops to zero, (goes white), and a yellow exclamation mark icon, (very small), appears on the tray icon. Take no action, and after a while, it returns to the previous level. My view of this has changed this week as I have ben paying more attention to it. There are still times when the service is nil, but that icon is still green.

[cyberfish]

You need to check both signal strength and signal to noise ratio (SNR). Signal strength can fall due to geometry (i.e. as you move around the house, affected by shape and relative orientation of antennas not just size) and SNR can fall due to interfering sources (say, a neighbour's Wifi or some other RF source turning on and off - which would explain the intermittent behaviour).

A signal strength meter doesn't necessarily report just YOUR signal level. It can also report the total level due to your signal and interfering sources in the relevant bands. Interfering sources, by definition, reduce your SNR. In other words, you can appear to have a good signal level but lose out due to SNR levels.

Check what WiFi channels are being used. A lot of Wifi routers default to using the same channel (even from different vendors) and need to be specifically configured to use different channels to avoid interference. Some routers do have a mode of picking an optimal (least interference) channel, but not all do that particularly well. Most (non-router) devices scan, but it doesn't hurt to look up what settings they use for searching (some are configured to a particular channel).

It's possible the wife's laptop (on your desk) is sitting in a sweet spot. Or that its wireless is leaking between channels, and causing interference for other devices.

The other thing to check is the power setting for all of your devices. If one is not putting out enough power it (or devices communicating with it) may have trouble. Power saving features typically affect that, if enabled.

Usually the icon shows "link quality", which is a heuristic calculated based on signal strength and noise floor (hence SNR).

Wifi routers can be switched to different channels, if interference from other access points is really the problem. You cannot set channels on clients. That doesn't make sense.

Clients always scan all channels, and use the router's channel to talk to it, because well, you can't talk to a router if you are on a different channel.

Having played with enough wifi cards, my first guess would be TrendNet is BS and their driver sucks. Do you know what chip it uses, and if there is a newer driver for it (not from TrendNet)?

[cyberfish]

You need to check both signal strength and signal to noise ratio (SNR). Signal strength can fall due to geometry (i.e. as you move around the house, affected by shape and relative orientation of antennas not just size) and SNR can fall due to interfering sources (say, a neighbour's Wifi or some other RF source turning on and off - which would explain the intermittent behaviour).

A signal strength meter doesn't necessarily report just YOUR signal level. It can also report the total level due to your signal and interfering sources in the relevant bands. Interfering sources, by definition, reduce your SNR. In other words, you can appear to have a good signal level but lose out due to SNR levels.

Check what WiFi channels are being used. A lot of Wifi routers default to using the same channel (even from different vendors) and need to be specifically configured to use different channels to avoid interference. Some routers do have a mode of picking an optimal (least interference) channel, but not all do that particularly well. Most (non-router) devices scan, but it doesn't hurt to look up what settings they use for searching (some are configured to a particular channel).

It's possible the wife's laptop (on your desk) is sitting in a sweet spot. Or that its wireless is leaking between channels, and causing interference for other devices.

The other thing to check is the power setting for all of your devices. If one is not putting out enough power it (or devices communicating with it) may have trouble. Power saving features typically affect that, if enabled.

Usually the icon shows "link quality", which is a heuristic calculated based on signal strength and noise floor (hence SNR).

Wifi routers can be switched to different channels, if interference from other access points is really the problem. You cannot set channels on clients. That doesn't make sense.

Clients always scan all channels, and use the router's channel to talk to it, because well, you can't talk to a router if you are on a different channel.

Having played with enough wifi cards, my first guess would be TrendNet is BS and their driver sucks. Do you know what chip it uses, and if there is a newer driver for it (not from TrendNet)?

[Fossaw]

I swapped the Trendnet cards for some by TP-Link. Absolutely no difference, they worked sometimes, not others.

I've now reinstalled wired.

[gemera]

I had a feeling that might be the case. The signal under those conditions is easily made variable simply by doors in both rooms being open or closed etc or even someone standing briefly near the router etc.