@Gustavo Calvino Torres Hope your issue has been resolved. As Sander mentioned, this could be a transient failure.
I see that "Add device" button is greyed out. Do you have necessary permissions to add devices?
You could also check the below information and see if that helps resolve the issue.
If the IoT Hub is behind a private end point and public access set to Disabled or not allowing the IP address of the client to access it, you will receive these type of error as mentioned, "Unable to retrieve devices. Please ensure your network connection is online and networking settings allow connections from your IP address."
If you need to keep it private then you need for example a VM in the same VNet to access the Azure IoT Hub and manage the devices.
Please have a look at the below documentations for more details to secure Azure IoT Hub connectivity and resolve any errors may occur due to network access.
Managing public network access for your IoT hub
IoT Hub support for virtual networks with Private Link and Managed Identity
Please let me know if you have any further queries.