One of my ISP's Tech's and I had a long talk today about the modem and the wireless signal.
The modem provides the internet connection but the wireless can fluctuate because of other residents around you that are wireless, cell phones and home phones the Tech told me the frequencies that they are on can effect the wireless strength.
The Tech suggested to try the new modem he gave me and if the wifi continues to weaken try the wired cable that he provided. Should it still persist the company suggests to purchase an additional router of my own and have them turn the modem that they gave me into a bridge and that would help the wifi from fluctuating as much as it has.
The Tech also mentioned that they could change the channel and that could help.
If your ISP does give you a new modem make sure they update the firmware.-::-
My wifi was exceedingly slow until the Tech updated the firmware on the modem.
If it continue's you could ask your ISP for a good will adjustment to your bill for the days that the wifi runs slowly or if your network keeps going down.
A Tech can check the modem and see if there is trouble in the lines-
If they do find errors they are trained to correct that or otherwise use their expertise to troubleshoot the issue.
Keep in mind that the more devices you have that pulls on the modem/router and can effect the wifi.
For example when the Sony PS3 is running a game (but not online) the wifi signal on my Slackware machine is crappy and if my Android device and laptop are on the wifi is really bad sometimes.
Your Intel 6200 network interface card is most likely already being supported by the module/driver that came with the version of the kernel your system is using. Not much more you can do with that; least I don't think so:-
For some reason when I ran the speed test it was slow at getting started too.
Hope that helps-