Issue using 1Gbyte Connection

Hi,

I recently upgraded my Internet Speed to 150mb/s, thus I need to use a Gbyte Connection in order to achieve this speed. Unfortunately, my Dell Laptop (XPS 14Z), does not allow me to select a 1GB connection in the Device Manager. I only have the option to choose between 100Mb/s and 10Mb/s, but not 1000mb/s. The Network Adapter is called Atheros AR8151 PCI-E Gigabit Ethernet Controller, so I assume that the adapter is capable of establishing such connections. My router is also capable of 1GB/s and all ports are set to 1GB/s outlet. This means it is definitely an issue of the Adapter.

Do you have any advice what I should do in order to fix this issue?

Specs:

Dell XPS 14 Z

Atheros AR8151 PCI-E Gigabit Ethernet Controller

Windows 7