WRT54GS running slow for 1 month for no apparent reason

Question

Hi guys,
It's my first post here and I've read a few hints regarding slow wireless connections however I seem to have exhausted my alternatives to fix the problem.
My scenario:
- 1 Orange Wanadoo Livebox ADSL modem/router
- 1 WRT54GS wireless router
- my laptop (only user in the network)
So I have my livebox router configured to IP 192.168.1.1. From the yellow port, an ethernet cable connects to LAN (not the WAN) port of the WRT54GS. This router is configured with "automatic configuration - DHCP" and local IP 192.168.1.2 and internal DHCP server is disabled (since the livebox is already providing a DHCP server). It's running in Gateway mode. I understand this configuration essentially makes the WRT54GS an access point. I opted for this configuration so I don't need to have 2 networks, one for the orange modem/router and another one for the linksys, leading me to added complexity and double NAT port forwarding configuration..
I've been using it happily like this for a while, however 1 month ago the internet slowed down considerably. I run Network stumbler to make sure that I'm the only one using my channel, which I am. Also, there's no close channel numbers with a strong signal nearby.
Yesterday I decided to connect my laptop wired to the livebox modem/router. Running a download test I achieved consistently 750 Mbytes/s download. When I use my laptop wireless (through the linksys) I get max 350 Mbytes/s with some drop-outs that make it to a low of 25 Kbytes/s. The wireless connection also seems to break easily. I was running the wireless test with my laptop basically next to the linksys. Bluetooth was turned off, my phone was off and I have not acquired any new radio-waved devices lately.
So I don't know what else to do... could it be that the linksys actually has a problem with it ? I didn't try connecting wired to the linksys with my laptop because I need another ethernet cable, but the wireless definitely seems to have run kaput. Also, I tried to run the linksys web ping tool but for some reason it cannot ping my livebox 192.168.1.1 neither resolve domain names (?)
350 Kbytes/s doesn't seem like a bad thing, however it's half of what I get wired not to mention that the QoS also decreases a lot... I get terrible lags with regular internet browsing, sometimes only fixed by a refresh to the page I'm currently browsing.
Any hints appreciated

Answer 1

I assume that you mean that when you wired your computer to your router, or directly to your modem, that you got 750 kbytes/sec , and then wirelessly you got only 350 kbytes/sec.   Is that correct?
Wireless connections require more overhead, so wireless speed is usually 50% to 70% of wired speed.  You are running at 47% and lower, so it does sound like you are having a problem.
Are you running any peer-to-peer (P2P) software?  If so, this is a known cause for router slowdowns and disconnections.  The problems can occur even if the P2P software is not currently running on your computer.  If you are running P2P software, stop using it.  It can take up to 5 days for the router to clear its memory and work properly again. 
After a firmware upgrade, you must reset the router to factory defaults, then setup the router again from scratch.  If you have not done this since the last firmware upgrade, please do this now and see if it corrects your problem.  If you saved a router configuration file, DO NOT use it.
If the above do not correct your problem, then the next most common cause for this is simply poor wireless connections.  Note that you can have a poor wireless connection even if your computer shows "5 bars".
There are many causes for poor wireless connections, and many solutions:
In the router, give your network a unique SSID. Do not use "linksys". If you are using "linksys" you may be trying to connect to your neighbor's router. Also set "SSID Broadcast" to "enabled". This will help your computer find and lock on to your router's signal.
Poor wireless connections are often caused by radio interference from other 2.4 GHz devices. This includes wireless phones, wireless baby monitors, microwave ovens, wireless mice and keyboards, wireless speakers, and your neighbor's wireless network. In rare cases, Bluetooth devices can interfere. Even some 5+ GHz phones also use the 2.4 Ghz band. Unplug these devices, and see if that corrects your problem.
In your router, try a different channel. There are 11 channels in the 2.4 GHz band. Usually channel 1, 6, or 11 works best. Check out your neighbors, and see what channel they are using. Because the channels overlap one another, try to stay at least +5 or -5 channels from your strongest neighbors. For example, if you have a strong neighbor on channel 9, try any channel 1 through 4.
Also, try to locate the router about 4 to 6 feet above the floor, in an open area. Do not locate it behind your monitor or near other computer equipment or speakers. The antenna should be vertical.
Also, in the computer, go to your wireless software, and go to "Preferred Networks" (sometimes called "Profiles" ). There are probably a few networks listed. Delete any network named "linksys". Also delete any network that you do not recognize, or that you no longer use. If your current network is not listed, enter its info (SSID, encryption (if any), and key (if any) ). Then select your current network and make it your default network, and set it to automatic login. You may need to go to "settings" to do this, or you may need to right click on your network and select "Properties" or "settings".
If the above does not fix your problem, download and install the latest driver for your wireless card.
Some users have reported improved wireless performance by switching to WPA encryption.
If you continue to have problems, try the following:
For wireless g routers, try setting the "Transmission Rate" to 54 Mbps.
If you still have trouble, download and install the latest firmware for your router. After a firmware upgrade, you must reset the router to factory defaults, then setup the router again from scratch. If you saved a router configuration file, DO NOT use it.
Hope this helps.