Causes:
1. The system software is experiencing a temporary glitch.
2. The phone hardware is malfunctioning.
Solutions:
1. It is recommended that you try to restart the phone and try again.
2. You may reset the wireless settings to try again.
realme UI 3.0 & above versions: Settings > Search "Reset Phone " in the settings > Reset Phone > Reset network settings.
realme UI 2.0 & 1.0: Settings > Additional Settings > Backup & Reset > Erase all data(factory reset) > Reset network settings.
realme UI R & T & S & Go & U Edition: Settings > System > Reset options > Reset Wi-Fi, mobile & Bluetooth
Note: Performing this operation will not wipe any of your data.
If the above methods can not solve your problem, please back up your data and contact realme service center for further assistance.