Backup Copies to S3

You can do Direct or via a Gateway server that is up to you.  The following explains each method to help you out - Object repositories | Veeam Backup & Replication Best Practice Guide

If “Direct” is selected, the repository holding the source data will connect directly to to the S3 target, as opposed to if you select a “Gateway”, the traffic will be routed via that server instead. This may be necessary if you have some proxy system in place where the repository doesn’t have direct access to the internet, or if you want the traffic to flow over a specific link.

For cases where storage systems are used that require a gateway server to be selected, like a Data Domain for example, “Direct” will route via the gateway server specified in the settings of that repository.

If you’re using Direct, you don’t need to worry about a Gateway server, as Veeam connects directly to Backblaze. However, if you want to use a Gateway server, make sure the proxy settings are correctly configured on both VBR and Backblaze, ensuring the Veeam server has the necessary permissions and access. For better performance and ease of setup, Direct connection is typically recommended unless you have a specific need for a Gateway server. It’s also worth checking if any specific network/firewall configurations are needed for seamless connection with Backblaze.