2. Then slide down the settings page and click the cellular network option, as shown in the figure below.
3. Click the cellular data option on the pop-up page, as shown in the figure below.
4. Then click the voice and data options on the pop-up page, as shown in the figure below.
5. Finally, select 4G and turn off the VOLTE option, and the signal of Apple's mobile phone will be enhanced, as shown in the figure below.