In Hyper-V, in the Virtual Network Manager, you are adding a new EXTERNAL virtual Network.

After selecting the physical network card to bind it to your virtual network, you click “Apply” or “OK”.

You receive the following error message:

“Error Applying New Virtual Network Changes

Binding to External Ethernet failed

Cannot bind to my_nic because it is already bound to another virtual network”

To fix this issue, close your Virtual Network Manager and run the command line with administrative privilege. Type:

netcfg -u vms_pp

netcfg -l c:\windows\winsxs\amd64_wvms_pp.inf_31bf3856ad364e35_6.1.7600.16385_none_beda85050b13680c\wvms_pp.inf -c p -i vms_pp

Open the Virtual Network Manager again, and add your external virtual network.

The operation shall be successful now.

In my case, the issue happened after a physical failure of the server: I had to disable two faulty NICs in the BIOS and when restarting the server, Hyper-V got lost in the mapping of the virtual networks and the remaining NICs. So I removed all external virtual networks and tried to recreate each. And I had the error at the recreation.