@Veaceslav 

To block access to local wireless devices for users connected to the Guest network on EAP225 V3 with Firmware Version 5.0.3, follow these steps:

1. Access the EAP225's web interface by entering its IP address in a web browser.
2. Log in with your administrator credentials.
3. Navigate to the "Guest Network" settings.
4. Look for an option related to "Client Isolation" or "AP Isolation" and enable it. This feature restricts communication between clients connected to the same wireless network.
5. Save the changes and apply the configuration.
6. Test the Guest network by connecting a device and verifying that it can no longer access local wireless devices.

Note: Having an Omada controller is not necessary for this specific task. The configuration can be done directly through the EAP225's web interface.

For more detailed instructions and specific menu options, please refer to the user manual or documentation provided by the manufacturer. You can also view the EAP225's user manual View Here View Here for additional guidance.