When I look at the wi-fi status, I see that I have a 4 or 5 bar signal quality, but my connection speed ranges from 6 to 20 mbps.
Is there anything I can do about the slow connection? When I run a speed test I usually have a good ping, but sometimes it spikes up to 200, and the download and upload speed always remain around 1mbps.
We have to note that the results from an internet speed test can be deceiving since your internet connection may fluctuate; the best way to test it is within your wireless local area network.
If you still get poor results after a local file transfer you may want to update your wireless driver, update your router's firmware, verify if your router is in the best possible location, move away interfering devices and use the least crowded wireless channel. The article below may be of further help.
http://www.intel.com/support/wireless/wlan/4965agn/sb/CS-028449.htm Wireless Networking; How do I improve my 802.11n wireless performance?
I changed the 2.4 ghz band channel to 11 and it seems much more stable, but which channel width should I select: 20 Mhz or Auto (20mhz or 40 mhz)
I didn't do this for the 5 ghz band since I'm pretty sure nothing uses it.