If you’ve just bought a smart WiFi robot vacuum, it may take a couple or so tries before you successfully connect it to your WiFi network.
Try resetting your router to see if it will connect.
Also make sure you are using the recommended WiFi frequency. Some robot vacuums can work with 2.4GHz routers only while others support both 2.4GHz and 5GHz.
You can also try setting a new password (some robots may specify an alpha-numeric password), checking that the robot vacuum is docked in and charging and that your WiFi network is strong enough.