I do not currently have access to the computer with the issue, to I am sorry if this question is a bit vague. I only need to know how to troubleshoot and not the actual solution.
Right, I have a USB WiFi dongle, its a D-Link Wireless N type, with the RTL8192CU showing when doing a lspci.
My WiFi works fine after booting my computer, but after some use, opening some tabs in firefox, my 8Mbit connection seems more like 512Kbit, instead of download rates of 700+ I get 40 or 50. It stays slow even after I close all tabs, and halt all internet activity.
However, sometimes I reset the connection by reconnecting, and it speeds up again, if not, and sometimes that does not work, I pull the dongle out and plug back it and speed is back up to full.
I thought maybe its my linksys WRT54GL router, but I connect to that using my phone while the slowdown is happening, and I do not experience the same slow less on the phone. So I have ruled that out. The ping times are also ok, with 0.8ms pings to the router, or thereabouts. Also worth noting is that I have been using this same dongle under Windows 7 and 8 for a year and never had any issue.
How do I troubleshoot this issue? what kind of things should I be checking?
Running an up to date Linux Mint 17.1.