When you want to rename a network adapter and you go “Cannot rename this connection. A connection with the name you specified already exists. Specify a different name.” You get this message for examle exwhen you changed the network card and you want to change the name of the new one to the same name the old one had.

Solution is to remove the old unused network adapter:

1.Click Start, click Run, type cmd.exe, and then press ENTER.
2.Type set devmgr_show_nonpresent_devices=1, and then press ENTER.
3.Type Start DEVMGMT.MSC, and then press ENTER.
4.Click View, and then click Show Hidden Devices.
5.Expand the Network Adapters tree.
6.Right-click the dimmed network adapter, and then click Uninstall