How to organize backup synchronization via the Internet?

Question

Data synchronization

Good afternoon!
There is a shared folder under MS Windows with archives. Veeam VEB backup software. Every day a backup copy is made, a differential is created. archive and synthetic full archive.
I'm trying to synchronize this shared folder with another PC via the Internet. Tried btsync and syncthing. Both each time fully copy the complete archive. The archive is large, there is no way to copy every day.
A synthetic full archive is obtained from the previous full one by merging with a diff and renamed.
Although the Syncthing fake says:
"Syncthing handles renaming files and updating their metadata in an efficient manner. This means that renaming a large file will not cause a retransmission of that file. Additionally, appending data to existing large files should be handled efficiently as well."
But in my case it doesn't work.
Advise software or how else to organize?

Answer 1

Make a separate policy in Veeam for copying to a second resource (even a ready-made copy), I'm not a fan of backup synchronization. Store only full and differential backups remotely. By means of system for copying robocopy helps a lot.

Answer 2

It will not work, since Veeam shovels the archive, and does not add blocks to it at the end. This is analogous to the fact that you have a large document, and somewhere in the middle of it the data has been changed. In order not to copy everything, the software must scan the entire file and copy only the blocks that have changed. Theoretically, rsync can do this.
Did I understand you correctly that you do synthetic full every day?