Just yesterday I bought the Linksys E3200 wireless router and had everything set up perfectly fine on my laptop (Windows 7) and main computer (Windows 8, Ubuntu). At least, that's what I thought until I booted up and selected Ubuntu. It detected the network and when I clicked on its name it allowed me to enter the Wi-Fi authentication code, but the tray icon kept playing the "connecting" animation for about a minute, before making a message pop up stating "Disconnected - You have been disconnected from the access point", or whatever it says.
I found this very odd as it worked perfectly fine with my Windows 8 installation on the same machine, Ubuntu could connect if I directly passed an Ethernet cord from my router to my computer, and the wireless connection originally worked before everything was set up with the router (i.e. its factory state, no WiFi password). I reset it to see if it could work again sans passcode, and it did, but disconnected again once I visited the configuration page and set up its wireless security once again.
Please help, I've tried everything from checking as many forums as I could to even installing WPA GUI (which I uninstalled after I found out it didn't do anything).