The Unexpected Data Drain
Apple’s ecosystem is heavily integrated via iCloud. If you own a Mac and an iPhone signed into the same Apple ID, they share network information. A feature called “Personal Hotspot” allows your Mac to utilize your iPhone’s cellular data connection when Wi-Fi is unavailable. By default, if your Mac loses its Wi-Fi connection, it might automatically search for and connect to your nearby iPhone’s hotspot without explicitly asking you. If you are halfway through downloading a 50GB video game update when your home Wi-Fi drops, your Mac will silently switch to your iPhone, potentially burning through your entire monthly cellular data cap in minutes.
Restricting Hotspot Access
To protect your cellular data plan and stop macOS from automatically connecting to your iPhone’s Personal Hotspot in the background, you must change a specific Wi-Fi setting.
Click the Apple logo in the top-left corner of the screen and select System Settings. In the left-hand navigation sidebar, click on Wi-Fi. In the main right-hand panel, scroll down past your current active networks. Look for a specific toggle switch labelled Ask to join Personal Hotspots. By default, this is often set to “Automatic.” Click the drop-down menu and change the setting to Ask to Join (or Never). Setting it to “Ask to Join” ensures that if your home Wi-Fi drops, a prompt will appear on your Mac’s screen asking if you want to use your iPhone’s data, giving you the chance to say no before any data is consumed.