Here is the definitive guide to doing it correctly. Warning: A hard reset will erase everything you have configured. You will need to set up your internet connection (PPPoE, Dynamic IP, etc.) and WiFi password from scratch.
Is your Xiaomi Mi Router 4C acting up? Forgot the admin password? Canโt connect to the configuration page? If you are experiencing slow speeds or weird glitches, a Hard Reset (also known as a factory reset) is often the fastest solution. How to Hard Reset XIAOMI Mi WiFi Router 4C
Unlike simply rebooting the router (turning it off and on), a hard reset wipes all your custom settingsโWiFi name, password, port forwarding rules, and parental controlsโreturning the device to its "out of the box" state. Here is the definitive guide to doing it correctly