The process for blocking devices from Wi-Fi may vary depending on the router you're using, but here are some general steps that should work for most routers:

Access your router's settings page: Open your web browser and enter your router's IP address in the address bar. You can find your router's IP address in the router's manual or on the back of the router itself.

Log in to your router: Enter your router's username and password. If you haven't changed these, the default username and password will be in the router's manual.

Find the list of connected devices: Look for a section called "Attached Devices," "Device List," or something similar. This should display a list of all the devices currently connected to your Wi-Fi network.

Locate the device you want to block: Find the device you want to block from the list of connected devices.

Block the device: Depending on your router, there may be a "Block Device" button or checkbox next to each connected device. Click this button or checkbox to block the device from accessing your Wi-Fi network.

Save your changes: Make sure to save your changes before exiting the router's settings page.

Note that blocking a device from Wi-Fi only prevents it from connecting to your Wi-Fi network. If the device has cellular data or another Wi-Fi network it can connect to, it will still be able to access the internet.