Major Wireless Internet speed loss

I have recently had a slowdown of internet speed on my wireless laptops. Following are many details which may help in diagnosing the problem:

All three of the laptops are getting 3mbits/s when they should be getting 16mbits/s. My wired computer (wired through the router) gets approx 12mbits/s (I understand I probably won't get 16mbits/s).

All computers run Windows XP Pro.

One laptop has a Broadcom Chipset while another has a intel chipset. I do not know the third chipset.

I achieve the same speed regardless of range and signal. Laptops getting 3mbits/s 50ft away also get the same speed sitting on top of the router.

I have tried switching my router from a Linksys WRT54G to a Linksys WRT150N and have had the same problems. The first router was G, the second is draft N.

I have contacted Linksys support. After speaking to many helpers for hours, They could not find a problem.

Nothing is leeching the connection. My main connection would suffer the same as the laptops if it did. I tried putting encryption and passwords and got no results.

Ive tried all available channels (1-11) and get the same speed on all of them.

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Holosoth hath wroth:

Does that mean that it was working normally before the slowdown? In other words, is this a *NEW* problem? If so, it may be interference from a nearby wireless network. See if any of these sources apply:

I'll assume you have a cable broadband connection. What speeds does the ISP claim they can provide? Is that burstable or continuous? Locally, Comcast provides 8Mbits/sec, with bursts to perhaps

15Mbits/sec.

Since all 3 have the same problem, I doubt it's the laptops. However, it would be nice if you checked for driver updates.

Tere's a chance that you might be connected at 802.11b speeds instead of 802.11g speeds. It's also amazingly common to connect to the neighbors system instead of your own. Please check these. If your connection speed is 11Mbits/sec, there's your problem. Hmmm... are you on Comcast in Michigan?

Yeah, but that's to the ISP/internet, not the local wireless speed. To get the wireless speed you need to benchmark just the wireless part. It's quite easy using Iperf. I described it in detail here:

If you still get 3Mbits/sec using the above IPerf test, you're probably stuck in 802.11b mode. Check your wireless settings in the router and make sure you're actually connected to your own router.

Using the default settings? Latest firmware?

Be advised that some routers are really slow for thruput. See table at:

Turn on some filters and they're even slower.

It's really difficult to diagnose problems

Well, you have a mystery. There are just too many unknowns. What's needed are:

CAT5 to router. Download speed from internet. No wireless.
CAT5 to router running Iperf server. CAT5 on 2nd computer running Iperf client. Download and upload speeds. Should be about

80-90Mbits/sec with 100baseT-FDX connections.

CAT5 to router running Iperf server. Wireless on 2nd computer running Iperf client. Download and upload speeds. At 54Mbits/sec connection, should be about 20-25Mbits/sec.

With these numbers, I can try to point to which part of the puzzle is causing the slowdown.