There are two types of network adapters available for Hyper-V: network adapter and legacy network adapter. For the network adapter to work, integration services must be installed and enabled through the Virtual Server Client (VSC), which is part of the service installation. If you can’t install integration services because of your OS, you can’t use the network adapter. Instead, you need to add a legacy network adapter, which doesn’t rely on integration services and instead emulates an Intel 21140-based PCI Fast Ethernet Adapter. The legacy network adapter is also required if a virtual machine (VM) needs to boot using a network. Use the Add Hardware option to add a legacy network adapter to a VM.