MAC randomization on Apple devices
From iOS/iPadOS 18 and macOS 15, Apple’s Private Wi-Fi Address has three modes:
| Mode | Behaviour | Default for |
|---|---|---|
| Off | The device’s hardware MAC is used | Any |
| Fixed | A stable random MAC, the same for that SSID | Encrypted networks |
| Rotating | A random MAC that changes about every two weeks | Open networks |
Because guest networks are usually open, the default becomes Rotating, so a device presents a new MAC roughly every two weeks. Since whitelisting and device registration rely on a stable MAC, this has two practical consequences:
- iPhone / iPad: with the defaults, no action is needed for short visits (under two weeks). For access that should last longer (for example BYOD), the user should set the network to Fixed (or Off) to avoid re-registering after about two weeks.
- MacBook: macOS 15 introduces this behaviour (previously the hardware MAC was always used), so a Mac may take a new MAC per SSID and require a fresh login. A user who wants to keep their registration can set Private Wi-Fi Address to Off under Settings → Wi-Fi → (network) → Network Details.