Hyper-V by default uses a dynamic MAC address – which means that Hyper-V will generate an initial MAC address for each network adapter, either for VM (vmNIC) or for the host (vNIC), and it will regenerate the MAC address if it believes it is necessary.

And if you make your device forget the network, it will also forget the private address it used with that network, unless it has been less than 2 weeks since the last time it was made to forget that network.Since Hyper-V’s inception back in 2008, you can configure a virtual machine to use a dynamic or a static MAC address for any given virtual network adapter. Starting with iOS 15, iPadOS 15, and watchOS 8, if your device hasn’t joined the network in 6 weeks, it uses a different private address the next time it connects to that network.If you erase all content and settings or reset network settings on the device, your device uses a different private address the next time it connects to that network.In some cases, your device will change its private Wi-Fi address:

This unique MAC address is your device's private Wi-Fi address, which it uses for that network only. Starting with iOS 14, iPadOS 14, and watchOS 7, your device improves privacy by using a different MAC address for each Wi-Fi network. This allows a kind of user tracking or profiling, and it applies to all devices on all Wi-Fi networks. If the device always uses the same Wi-Fi MAC address across all networks, network operators and other network observers can more easily relate that address to the device's network activity and location over time. To communicate with a Wi-Fi network, a device must identify itself to the network using a unique network address called a Media Access Control (MAC) address.

How to convert mac address