Hello ThreeM, I am sorry to hear that you are having issues with your system when trying to connect to a router.
Keep in mind that you do not have a defective N7260 adapter since it is capable to connect to the Cisco router.
Some recommendation I could give you are the following:
- Reset the router and leave it without security just for testing.
- Check if there is a firmware update the router may need.
- Since you are able to use Skype when connecting to the Dlink router, check if there is any application filter or port filter that is not allowing you to use those specific applications (Dropbox/browser).
- Please check if and Antivirus or Firewall software may be blocking