If you are having trouble connecting to "DU Wireless", follow these steps:
Go to "System Preferences" and select “Network”
Select “Wi-Fi” then "Advanced"
Under Preferred Networks, remove “DU Wireless”
Next, search for "Keychain Access" (using the search tool) and select Certificates
Right click and delete the “DC2012R2-2.dom.edu” certificate.
Next select “Passwords”
Right click and delete “DU Wireless”
Restart the computer.