Issues with network stability/speed

Toshiba / Satellite a305
January 24, 2009 at 18:21:42
Specs: Windows Vista, Intel Core2 Duo T8100 @ 2.10GHz, 3GB RAM
I have 2 issues. First, laptop A will drop off the network even though it sees the network with excellent signal strength. When I take off the security, it will connect for a limited time with slow speeds (<1 Mbps). Laptop A runs XP with the firewall turned off and is located in the room with the router only a few feet away.

The second issue is laptop B is rather slow as well. Laptop B can usually get about 3 Mbps. Laptop B runs Vista with the firewall turned off and is located in the adjacent room from the router only a few feet away through the wall. Both laptops have been rebooted several times.

Just moved so setting up the network for the first time in the new house. However, had these issues in the old house as well. At the old house I had Verizon FIOS 15Mbs service (verified speed hard wired), but wireless network speeds were much less.

At the new place, we have Comcast cable Internet. The supplied RCA DCM425 cable modem is connected to the wall, with our Linksys WRT54GX4 connected to the cable modem.

When I was setting up the wireless router, I would have speeds of 12-30 Mbps wired directly to the Linksys router, so I know the ISP and modem/router are working well. The network signal strength is excellent. I use WPA security encryption, which works fine on laptop B, and only intermittently allows connection to laptop A.

I set up the wireless router using these instructions which worked perfectly (http://linksys.custhelp.com/cgi-bin/linksys.cfg/php/enduser/std_adp.php?p_faqid=3686). The router currently has all its default settings except the change in the instructions above. I also have played with the channel, switching from the default of 6 to 11 with limited improvement.

1) Any ideas why laptop A drops off the network even though it sees it and has excellent signal strength? When tying to connect it takes a long time and then seems to time out.

2) What’s the deal with the slow wireless network? The router is supposed to handle up to 54 Mbps and I know when wired to the router I am getting 12-30 Mpbs. Why are the laptops only getting 1-3 Mbps on the wireless network? What can I do about it? Realistically, with this setup, what wireless speeds should I be hoping for?

Thanks so much for your help, let me know if you need more details about the setup.


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#1
January 24, 2009 at 22:02:05
First, what they don't tell you about 54G and 54Mbps wireless is that you only get half of that in actual throughput speed, about 26Mbps. (The rest is taken up by networking overhead).

Second, unless you have multiple radios in that wireless router or access point (not antennaes, but actual radios), that router is like one port for network connectivity, so that speed gets divided between all active connections. So if you got two wireless clients actively communicating, that's 26Mbps divided by 2 = 13Mbps.

Third, if there's any type of interference or some signal degradation caused by any of the wireless clients, such as distance or by walls, the router will kick down the speed to improve signal strength for that one client, which will affect everybodys speed. So if the router kicks down to 36Mbps, divided by 2 because of overhead (18Mbps), divided by 2 active wireless clients, now you only have about 9Mbps max available for each client.

54G works on the 2.4Ghz spectrum. 2.4Ghz cordless phones can cause interference in this spectrum and I think newer cell phones do also. (Microwaves also affect wireless communication when running.)

There are only 3 non-overlapping channels for 54G, channels 1, 6 and 11. You may have more wireless network neighbors around in your new house than the old one that can be causing interference. Even if the Windows or the cheapy utility that comes with consumer wireless cards says the signal strength is excellent, they are not true spectrometers and you may still be getting noise from something else that's interfering with the signal.

Also, different building materials in houses or wall construction can cause noise or interference. Even in the same room, if the signal is bouncing off the wall all over the place it's going to result in a bad signal.

Cheap consumer wireless routers/access points experience performance degradation when using encryption because the hardware is of cheaper design. There's a reason commercial wireless access points cost $500 and up versus $60 consumer routers.

Last, sometimes routers just start going bad and their performance can start degrading over time.

I hope these points help in understanding all the variables that can affect wireless performance.

You said you tried channel 6 and 11, try channel 1 also. Also, are there nearby wireless networks with the same name (SSID) as yours? If so, your computers will get confused and try to intermittently connect to them, causing communication problems. Make sure you SSID is unique. You may also want to try upgrading to an N router. You won't get N speeds if your computer are only G capable, but N routers have diversity antennas that can help with signal quality on the router side.

Assume that I already did an Internet search.


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#2
January 25, 2009 at 05:46:16
First, what they don't tell you about 54G and 54Mbps wireless is that you only get half of that in actual throughput speed, about 26Mbps. (The rest is taken up by networking overhead).

The usual rate is about 10 to 20% in overhead. Not 50%

Not that wireless is my favorite medium. Quite the opposite and not just because of it's inherent insecurity. It's given to all kinds of issues like the one's the OP posted about here. My preferance always has, and always will be, a wired solution.

Laptop A runs XP with the firewall turned off and is located in the room with the router only a few feet away.

Ok stupid question. With the laptop only a few feet from the router, why aren't you plugging that laptop into the router with a network patch cable? You would get better reliability and bandwidth that you could ever hope to get with wireless...........period. If you have a router with only a single LAN port and it's in use. Spend $50.00 and buy a small 8 port switch. That would fix the problem with laptop A.

2) What’s the deal with the slow wireless network? The router is supposed to handle up to 54 Mbps and I know when wired to the router I am getting 12-30 Mpbs. Why are the laptops only getting 1-3 Mbps on the wireless network? What can I do about it? Realistically, with this setup, what wireless speeds should I be hoping for?

Ok, at the very least you should be getting around 80 Mbps when wired (on a 100 Mbps connection). If you're getting only 12-30 wired and 1-3 wireless, I suspect there's something wrong with your router. If you have any friends with a wireless router you could borrow long enough to test (invite your friend over and have them bring the router) I would do so and see if things don't improve. If they do, your router is in need of replacing.

However, whenever people who aren't network technicians start quoting numbers at me I always have to ask how they came up with them. So, how did you come up with those numbers?

Analyst

You said:

You may also want to try upgrading to an N router. You won't get N speeds if your computer are only G capable, but N routers have diversity antennas that can help with signal quality on the router side.

A little soon for that advice. As of today, N is not yet a ratified standard. Personally, I would wait a little bit until it is. Predictions are, it will be ratified before the end of the 1st quarter of this year.



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#3
January 25, 2009 at 06:34:11
CurtR,

10-20% overhead applies to wired connections. With wireless, overhead is closer to 50%.
Partly because B/G can only either listen or talk, not both at the same time.

These articles from Wikipedia and Cisco explain some of the limitations of 802.11.

http://en.wikipedia.org/wiki/802.11

http://www.cisco.com/en/US/products...

Last, if you have a wireless router and use a throughput tester (I was going to suggest WildPackets NetDoppler, but they may have merged it with their OmniPeek product), you will see the actual throughput you get is closer to half the stated speed.

Assume that I already did an Internet search.


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Related Solutions

#4
January 25, 2009 at 10:41:02
Thanks guys for the help thus far...

I havent made any changes yet and here's the update.

I ran another speed test hardwired to the Linksys and got 26.8 Mbps. Right after, I connected directly to the cable modem and got 27.0 Mbps. So I am pretty convinced that the Linksys is working just fine.

Also, laptop B has been running closer to 10 Mbps this morning on the wireless network. So, I am running at about 38% capacity over wireless.

My biggest problem is that laptop A can see the network with excellent signal strength, but cannot connect (it times out). Even if it does connect (most of the time without security), it is for a short time with about 1 Mbps.

The reason I do not want to just give up and connect laptop A hardwire, is that I want to capability to use it anywhere in the house.

Also, the hardwire speeds to the linksys and cable modem are using laptop A, so its a wireless issue with the XP laptop.

The network name is very unique, so that is probably not an issue.

Any other suggestions to speed up the network or get the XP laptop on would be appreciated.


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#5
January 25, 2009 at 14:25:46
One thing you can try is move the router and laptop to differant rooms and see if that changes anything or if you get better than 1Mbps stated. If so, there's something in the room or air causing interference in that part of the house.

You can also try deleting and recreating the connection in Windows, or try an updated driver for the wireless NIC.

Assume that I already did an Internet search.


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#6
January 26, 2009 at 05:52:46
10-20% overhead applies to wired connections. With wireless, overhead is closer to 50%.
Partly because B/G can only either listen or talk, not both at the same time.

Ouch! (he says as he smacks himself on the forehead with the palm of his hand).

You are correct, and, I was thinking wired for some reason when I wrote that.


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#7
January 26, 2009 at 07:04:14
It's all good, Homey.

Assume that I already did an Internet search.


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