Microsoft Loopback Adapter Windows 11 |link| Jun 2026

It exists only in software, simulating a NIC.

Users sometimes find that after setting a static IP address on a loopback adapter, the settings are lost or revert to automatic.

A known behavior, particularly with the KM-TEST adapter, is that it may become unstable after a ping or two, replying with "General Failure" until it is disabled and re-enabled. This appears to be a sporadic driver behavior in some versions of Windows 11.

Microsoft Loopback Adapter Windows 11: A Complete Guide The (officially renamed as the Microsoft KM-TEST Loopback Adapter in modern Windows versions) is a hidden gem for network administrators, developers, and security enthusiasts running Windows 11. While your computer usually connects to the outside world, this virtual network interface allows you to simulate a network environment, testing network applications, and capturing traffic entirely within your local machine.

The (renamed to Microsoft KM-TEST Loopback Adapter in newer versions of Windows) is a virtual network interface used to simulate a network connection on a single machine. It is primarily used for testing network software, developing applications that require a network interface without having a physical one active, or troubleshooting connectivity issues. How to Install on Windows 11 microsoft loopback adapter windows 11

When using packet analysis tools like Wireshark, the loopback adapter enables capture of traffic that would otherwise be invisible because it never leaves your computer. Tools like Npcap (a Windows packet capture library) can utilize loopback adapters to monitor local network communications.

pnputil /enum-drivers

: Since Windows 8, it has been renamed to "Microsoft KM-TEST Loopback Adapter". Users should look for this specific name during setup to avoid confusion. Ease of Setup

Even with a straightforward installation process, you may encounter issues with the Microsoft Loopback Adapter on Windows 11. It exists only in software, simulating a NIC

The KM-TEST variant offers enhanced capabilities compared to earlier versions, including better integration with modern Windows networking stacks and improved stability. When installing a loopback adapter on Windows 11, this is the driver you'll actually select from the list of available network adapters.

Any traffic sent out through this virtual adapter is immediately received back by the same machine. This creates a standalone network environment entirely within the Windows 11 operating system, isolated from external hardware.

Windows 11 does not enable the Loopback Adapter by default. Because it is a virtual hardware driver, you must install it using the Device Manager. Step 1: Open Device Manager Press on your keyboard. Select Device Manager from the Power User menu. Step 2: Launch the Hardware Wizard

For the loopback adapter to function correctly for testing (so it doesn't rely on DHCP), you should assign it a static IP address. This appears to be a sporadic driver behavior

Microsoft Loopback Adapter —now renamed the Microsoft KM-TEST Loopback Adapter

: Troubleshooting internal network stack operations or emulating specific network environments for development.

Safely test network-dependent applications on a single machine.