Stop your Mac joining the wrong Wi-Fi network

Why it happens

Your Mac remembers every network you've joined and can join any of them by itself when it's in range. When several are nearby, like a guest network, a neighbour's or a phone hotspot, it may pick one you didn't want. Turning off automatic joining for that network leaves the Mac to choose the ones you do want.

How to fix it

1. Open the Apple menu, choose System Settings and click Wi-Fi.

2. Click Details… next to the network you don't want your Mac to join.

   Wi-Fi›Details…

3. Turn off Automatically join this network and click OK. Your Mac keeps the password, but only joins when you choose the network yourself.

   Wi-Fi›Details…

4. Network not nearby, so no Details… button? Click Advanced… in Wi-Fi settings, find it under Known Networks, click the … button next to it and turn off Auto-Join.

   Wi-Fi›Advanced…

5. Now open Details… for your own network and make sure Automatically join this network is turned on, so your Mac goes back to it.

Still not fixed?

1. To remove a network for good, open its Details… and click Forget This Network… at the bottom.

   Wi-Fi›Details…

2. If your Mac keeps jumping onto your iPhone's hotspot, change Ask to join hotspots in Wi-Fi settings so it doesn't join on its own.

   Wi-Fi›Ask to join hotspots

3. If your router shows two names, such as one ending in 5G, join the 5 GHz one and turn off automatic joining for the other.

4. Networks you've joined on your iPhone or iPad can appear on your Mac too, because Wi-Fi passwords sync through iCloud Keychain. Turn off automatic joining for them on the Mac in the same way.

5. If your Mac still leaves your home network for another one, restart your router and your Mac. If it keeps happening, contact Apple Support, or your internet provider if other devices drop off too.