To register your device with Azure Notification Hubs, you need to follow the steps mentioned in the documentation**.** However, if you are facing issues while registering your device from a specific server IP, it might be possible that the IP is not whitelisted in your Azure Notification Hubs. You can check the list of IP addresses that are allowed to access your Azure Notification Hubs by following these steps:
- Go to the Azure portal and select your Notification Hub.
- Click on the "Firewall and virtual networks" option under the "Settings" section.
- Check if the IP address of your server is listed under the "Allowed IP addresses" section. If not, you can add it by clicking on the "Add" button.
If you are still facing issues, you can try to diagnose the issue by following the steps mentioned in the "Diagnose dropped notifications in Azure Notification Hubs" documentation**.** If you need further assistance, please provide more details about the issue you are facing.