Stop your Mac joining your iPhone hotspot when you're at home

Why it happens

When your Mac thinks no Wi-Fi network is available, it can jump onto the Personal Hotspot of an iPhone signed in to the same Apple Account. A weak home signal, or a router that was restarting for a moment, is enough to trigger it. Once it's on the hotspot, it may stay there and quietly use your mobile data.

How to fix it

1. Click the Apple menu, choose System Settings, and click Wi-Fi in the sidebar.

2. Scroll to the bottom of the page and find Ask to join hotspots. Pick Ask to Join if you still want the option when you're out, or Never if you only want it when you choose it yourself.

   Wi-Fi›Ask to join hotspots

3. If your Mac is on the hotspot right now, click your home network in the Wi-Fi list to move back to it.

4. When you do want the hotspot, for example on a train, pick your iPhone from the Wi-Fi list or the Wi-Fi menu in the menu bar.

Still not fixed?

1. Still switching by itself? Your iPhone may be saved as a known network. While your Mac is on the hotspot, click Details… next to your iPhone and turn off Automatically join this network. If it isn't connected, find it under Known Networks, click its … button and untick Auto-Join.

   Wi-Fi›Details…

2. Check that your Mac rejoins home by itself. In Wi-Fi settings, under Known Networks, click the … button next to your home network and make sure Auto-Join is ticked.

   Wi-Fi

3. If the home signal is weak where you sit, that's the real cause. Restart the router by unplugging it for 30 seconds, and try moving it somewhere more open.

4. On your iPhone, you can also open Settings, tap Personal Hotspot and turn off Allow Others to Join while you're at home. Your own devices may still see it, so the Mac setting above matters most.

5. If your Mac keeps dropping your home Wi-Fi even next to the router while other devices stay connected, contact Apple Support. The Wi-Fi hardware may need a check.