Apple USB or Thunderbolt to Ethernet Adapters: First time setup
When you connect a new Apple USB Ethernet Adapter or Apple Thunderbolt to Gigabit Ethernet Adapter to your Mac, a prompt appears asking if you'd like to use this device for a new network configuration.
Follow the steps below to quickly set up an Internet connection through one of these adapters if you've not used that adapter with your Mac before.
From the Apple () menu, choose System Preferences.
Choose Network.
Connect your Thunderbolt or USB Ethernet adapter.
Select the device and configure your network.
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You may need to go through these steps again if you use a different adapter with your Mac, if you get a new Mac that's never used the adapter before, or in some cases when you've performed a migration from one Mac to another and the network configuration information (from the previous Mac) is not retained.