Check whether Wi-Fi+ is enabled.

Open Settings, search for and touch Wi-Fi+, and check whether Wi-Fi+ is enabled. (EMUI 5.X: Go to Settings > Wi-Fi > Wi-Fi+.)

If the Wi-Fi+ feature is enabled when you are away from the Wi-Fi coverage area and your phone does not connect to another Wi-Fi network, the Wi-Fi switch will automatically turn off. When you return to the Wi-Fi coverage area, the Wi-Fi switch will automatically turn on for your phone to reconnect. (Note: In EMUI 9.0 or later, the Wi-Fi+ feature will not automatically disable Wi-Fi.)

Check whether you have installed a third-party app that requires a Wi-Fi connection.

If third-party apps that require a Wi-Fi connection have been installed on your phone, they may automatically turn on Wi-Fi.

Check whether Send last location has been enabled in Cloud

If Send last location is enabled in Find My Phone, the Location and Wi-Fi switches will automatically turn on in order to locate the phone when the battery level is reduced to 10% and 5% respectively.

• You can swipe down from the status bar and manually disable Wi-Fi.
• If you do not want to use this feature, search for Find My Phone in your phone's settings and disable Send last location.