Private Wi-Fi Address: Fixed, Rotating or Off? (Random MAC Address Explained)

Your router lists a device with a hardware address you don't recognize. A reservation that worked for months suddenly stops working. Or the same phone keeps turning up as a new device. Very often the reason is the same: a private Wi-Fi address. In this video we'll look at what that is, how to spot one, and when you should change the setting.

As always, this is DeviceShelf's demo network, a made-up home with forty-four devices.

Let's scan and filter for the phones. Here are two iPhones. The first one shows Apple as the vendor. The second one shows no vendor at all.

The vendor normally comes from the first half of the hardware address, the MAC address. Manufacturers buy those blocks, so a lookup tells you who made the network chip. This address isn't from any block. The phone made it up. You can recognize such an address by its second character: a two, six, A or E means the address was assigned locally, not by a manufacturer. Here it's six E.

Open the device, and DeviceShelf says it right under the name: randomized MAC. It's a plain note, not a warning. Private addresses are the default on every current iPhone, Mac and Android phone, so half of a normal home network uses them.

Because the address can change, DeviceShelf doesn't rely on it alone. This phone also has a name, iPhone S E, so DeviceShelf recognizes it by its name. A device that has a private address and no name at all gets the same badge as a warning: after it rejoins, it would show up as a new device.

To match a device in your router with the phone in your hand, compare the address the router shows with the one the phone uses on this network. On an iPhone, the Wi-Fi details show it as Wi-Fi Address, right under the private address switch. If the two match, it's the same phone, whatever the router calls it. Compare at the same time and on the same network, though. An old entry in the router's list can carry an address the phone used weeks ago.

The setting lives on the phone, and it applies to one network at a time. On an iPhone, open Settings, Wi-Fi, and tap the info button next to the network. On a Mac with macOS Sequoia, it's in System Settings, Wi-Fi, under Details for the network. There are three choices.

Fixed means the phone uses one made-up address for this network and keeps it. That's the usual default on a network with WPA2 or better, and it's the friendly choice for a home network: the router sees the same address every time. Rotating means the phone picks a new address now and then. That's the default on open or weakly protected networks, like a café. And Off means the phone uses its real hardware address again. Android phones have the same idea under the network's privacy setting, where you choose between a randomized and the device's own address.

Most of the time a private address causes no trouble at all. It matters in three places. The first is a reservation in the router, which ties an IP address to a hardware address. If the phone presents a different address, the reservation no longer matches, and the phone gets a different IP.

The second is a filter list in the router that only lets known addresses in. And the third is alerts for new devices. In the timeline you can see a guest phone that went offline a few hours ago. Its address, B two, nine F, is a private one too. If that phone rotates its address, its next visit looks like a brand new device.

So what should you do? For your own phones on your own network, leave the private address on Fixed. That keeps the privacy benefit everywhere else and gives the router a stable address at home. In DeviceShelf, give the device a name, and it stays the same device in your list.

If you need a reservation, set the phone to Fixed for that network first, then reserve the address the router sees right now. Turning the feature off only makes sense where a network really depends on the real hardware address, and then only for that one network, not for every network the phone joins.

One more thing: before you change the setting, write down the network name, the time and the address the router shows. Change one thing, reconnect once, and check again. And don't post a full hardware address in a public forum. The last few characters and a time are enough for anyone who helps you.

So: a MAC address without a vendor whose second character is two, six, A or E is a private Wi-Fi address. DeviceShelf marks it and recognizes the device by its name. On your home network, Fixed is the setting that keeps everyone happy.

More videos about your home network are on our channel. DeviceShelf runs on Mac, Windows and Linux, at deviceshelf dot app.