When you create a VM on Hyper-V, by default the VM will have a virtual network (vNIC or Virtual Network Interface Card) to access the network. You can add other vNICs to this VM later, but the point here is that this VM must have a connection with a switch, or in this case a Virtual Switch.
Hyper-V has three types of Virtual Switch which you can choose from, depending on the traffic and destinations you want this VM to reach. The three types of Virtual Switch are:
Private: The Private Virtual Switch is a Virtual Switch that is not connected to the external network or the host itself. This means that a VM connected to this Virtual Switch can only reach VMs at the same Virtual Switch, as shown in the following figure:
Internal: The Internal Virtual Switch has an additional component for the host machine. This Virtual Switch allows you to connect a virtual network on the host to the itself. With that, the VMs can reach other VMs on the same Virtual Switch and the host,...