KB1735: The specified network name is no ... - Veeam Software
https://www.veeam.com/kb173522.02.2013 · Writing backup files to SMB shares over a slow or unreliable network, such as a WAN connection, is not recommended. Deploy a gateway server with a fast (Ethernet 100Mbps+) connection to the share. To rule out interference from a firewall, temporarily disable any software firewalls (including certain antivirus products) on the SMB client or server, as well as any …