(usually a pinhole next to the power button) for about 10–20 seconds while the device is powered on. Are you experiencing a specific error message
The classic ZTE web interface (192.168.0.1) is notorious for lagging or failing to save settings. Newer firmware versions rewrite the JavaScript backend, making menu navigation instantaneous and preventing the dreaded "Settings not saved" error. Zte Mf927u Firmware Update
The most direct method is using the built-in "Update Management" tool: (usually a pinhole next to the power button)