Wifi speed is WAY slower than ethernet

Your WiFI download speed should be about 20 mp/s, you do have a serious issue.

My advice is:

1: update your routers firmware

2: run a wifi sniffer to find out what channels other routers are on in the area and set yours way from theirs

3: follow the advice here and change all your passwords etc.

WiFi, Internet problems, possible solutions

WiFi security issues, at home and WiFi hotspots

4: if the router is still slow, consider replacing it, move closer to the router

Also do a survey of your area for sources of interference:

http://support.apple.com/kb/HT1365

Interesting that you found it to be the cause on your router. I just checked and on mine, QoS is on for both IPv4 and IPv6, and I get 100% of my ISP's speed, so it might not always be the cause. Sounds like it might depend on the type of router someone is using.

But if turning it off works in your case, that's good to hear.

Hello Sindox,

I also had the same problem. Initally my speed was 3.8Mbps. I have a Macbook Pro running Mac OSX 10.6.8. My router is a Dlink DIR-655 with QoS. I turned off the QoS and my speeds returned. I ran Speedtest.net and recieved 15.8Mbps. That is what I was suppose to get. Then I went back into my router and turned QoS back on and rebooted the router. I performed another speedtest and I recieved similar results 16.5Mbps. So you were correct in the QoS causing the problem. But why it was happending I don't know must be some sort of conflict with the QoS processing. One last piece of info this started to happen after I changed my DNS to OpenDNS. Not saying that was the cause but it could have been. Now everything is working perfectly. Maybe someone else out there had the same issue. Goodluck!

Since IPv6 was mentioned, if your ISP is not using/deploying it right now, consider disabling it on the Mac. Many routers freak out when a device starts hammering them for its global prefix. My 2Wire napkin holder wouldn't let me download a single patch from Apple till I shut IPv6 down for now.

Yes, we will all have to go live in the happy world of ginormeous IP addresses, but deployment has been dragging its feet since the start of the century.

It's supposed to be slower then LAN. Check this guide out: http://appuals.com/wi-fi-transmits-slow-speed-wired-lan/