When associating a virtual switch to a physical network connection, you always run the risk of causing your server to lose all network connectivity for a few seconds or until the virtual switch has been dissassociated from your physical network connection.
We always recommend making sure you have a KVMIP connected to your server before attempting this procedure. This is so that you can revert your changes in the event your server loses connectivity.
To order a KVMIP before beginning this procedure, please see here:
1- Using Remote Desktop, connect to your server.
2- Launch the Server Manager.
3-Select Hyper-V Manager from the Tools menu.
4- Launch the Virtual Switch Manager.
5- Create a new external switch.
6- Give a significant name to the new switch and associate it to your external network connexion.
(Note that the network name might be different than the one displayed in the screenshot below).
7- Make sure to check 'Allow management operating system to share this network adapter'
Your new virtual switch is now created and can be used to connect your virtual machines.