How do I stop my phone automatically joining an old Wi-Fi network?

Find that network in your phone’s Wi-Fi settings and choose between two actions: turn off its Auto-Join or automatic-connection setting, or forget/remove the saved network. Apple says users can turn off Auto-Join or forget a known network to stop a device from joining it automatically. [S1] Microsoft recommends removing remembered networks you no longer need and advises against automatic connections to networks you do not control. [S2]

If you might use the network again, disabling auto-join is the less final choice. If it is obsolete and you do not need it saved, forgetting it is a cleanup option. Menu names and steps vary by phone platform; use your device maker’s instructions if you cannot find the control. [S1][S2]

Ask yourself whether you expect to connect to this network again. If you might, turn off auto-join and keep it saved. Apple describes turning off Auto-Join for a known network. [S1] If you no longer need the network, choose Forget or Remove; Apple lists forgetting as another way to stop auto-joining, and Microsoft recommends removing remembered networks that are no longer needed. [S1][S2]

For a network you do not control, avoid leaving automatic connection enabled. [S2] The supplied guidance does not establish that every phone uses the same label or menu, so look for an equivalent control or check the phone maker’s instructions.

Try this general route: open Settings, look for Wi-Fi or wireless-network settings, and find the old network in the saved or remembered list. Open its details or options. If you want to keep it saved, switch off Auto-Join, Connect automatically, or the closest equivalent shown. If you no longer need it, choose Forget or Remove.

These are labels to look for, not guaranteed menu names. Apple’s instructions cover Apple devices; the supplied Microsoft guidance is not phone-specific and directs users to the device maker for exact phone steps. [S1][S2] If the network or control is hard to find, check the maker’s help for your phone rather than changing unrelated settings.

Change only the entry for the old network. For your home network, leave its setting alone unless you also want to change how the phone connects to it. Then disable auto-join for the old entry if you may need it later, or choose Forget if you are done with it. Apple describes these options for known networks, but another phone’s controls may differ. [S1]

For example, assuming these are the names shown on your phone, leave “Home-WiFi” unchanged and either turn off auto-join for “Old-Apartment-WiFi” or forget that entry. Before confirming, check that you selected the intended network, not one with a similar name. This example illustrates the choice; it does not claim that a particular phone uses these menu labels.