Box 1: never -
The 10.2.9.0/24 subnet is not whitelisted.
Box 2: never -
After you configure firewall and virtual network settings for your storage account, select Allow trusted Microsoft services to access this storage account as an exception to enable Azure Backup service to access the network restricted storage account.
Reference:
https://docs.microsoft.com/en-us/azure/storage/files/storage-how-to-use-files-windows
https://azure.microsoft.com/en-us/blog/azure-backup-now-supports-storage-accounts-secured-with-azure-storage-firewalls-and-virtual-networks/
