One laptop w/ USB wireless adapter causes significant drop in wireless speeds for others on the network.

[Shmori]

Let me start out by stating that the router in use is a Linksys E3000 with the most up to date firmware for it (v1.0.6) and I pay for a 12Mb/s 1Mb/s connection and it is located downstairs in my home. It's currently set to Auto channel width and channel for both 5GHz and 2.4GHz settings with WPA2/WPA Mixed Mode security.

There are 3 of us that currently live in my house and one of my roommates who lives upstairs uses a laptop with a USB wireless network adapter. Any time he connects laptop to our home network the entire network slows down from ~15-20ms ping 12/1 connection down to ~1.8k-3k ping 2.54/0.15 speeds.

Without this laptop connected to there are zero issues, we can have 2 apple tv's going and the other 2 roommates gaming comfortable on pc's with no noticeable drop in speeds, yet the moment this laptop connects it goes to shit. I gave the guy upstairs a wireless network adapter that I've used with the same router/modem for years and the issues still persist whenever he connects.

I've done countless google searches and forum crawls to attempt to fix these problems but I can't find anything that seems to work with it. If someone could point me in the right direction to find a solution to this that would be great.

 

[BadAsAl]

Make sure he is not file sharing (torrent) or something like that. If he is hogging bandwidth, especially upload bandwidth, it can slow you right down.
If he connects using LAN cable, does it do the same thing?

 

[Pooneil]

+1 on torrents. He probably doesn't understand how to use his app. Tell him to clear the old torrent files from his app and move the completed downloads to a new location on the hard drive. Or just gang up and change the wifi password without telling him. Running a torrent upload server can draw harassment from various sources.