https://helpcenter.veeam.com/docs/backu ... ml?ver=110
Obviously this makes sense, without routing in place from the Veeam Backup server to the SureBackup proxy appliance, there is no way for them to communicate.If you assign to the proxy appliance an IP address from the same network where the backup server is located, Veeam Backup & Replication will automatically add a new route to the routing table on the backup server. If you assign to the proxy appliance an IP address from a different network, you will have to manually add a new route to the routing table on the router in the production network. If you do not add a new route, tests and application scripts will fail and you will not be able to access VMs in isolated networks.
However, if someone is backing up VMs at a remote site, they probably have a Veeam proxy at that site to handle dedup, compression, writing to the backup location (local disk, NAS, etc.). Why not do this instead?
By having the Veeam proxy run the SureBackup tests, the automatically created route will be sufficient in a lot more situations, as that proxy is a lot more likely to be on the same subnet as the SureBackup proxy.