I just bought a D-Link DIR-655 router, and I've noticed a significant difference between the wired and wireless speeds when browsing the internet. My cable connection is supposed to have a speed of 20 Mbps, but I noticed today that I can only get about 11 Mbps over a wireless connection. Running the same test (using speedtest.net), I found that I could hit just over 20 Mbps using a wired connection, so the internet connection isn't the problem.
I've tried adjusting the channel to Channel 11 (rather than letting the router choose – it was on Channel 1 to begin) after looking at the other channels in use in this area. I even tried disabling the encryption (WPA2) to see if that would help, but it didn't. The wireless card in my four year old laptop can't do 802.11n, so the router is set to connect on G only.
The Dell utility that came with the driver for the wireless card (built-in, not external) on my laptop shows no significant noise on the connection. Windows (XP, SP3) is showing the connection has 'Excellent' signal strength and the speed there is reading as 54.0 Mbps as is normal for a G connection.
I'm not sure what else could be disrupting the signal. The router is unfortunately right next to a speaker, and there is a cordless telephone in the room, but I would have expected that these devices would show up as noise in the utility if they were a problem. My assumption is that the problem is with the router itself, but I am unable to determine how to confirm/correct this.
Any suggestions would be much appreciated.