Can you elaborate on the process you are following for seeding? You mention "restores" in your post which typically aren't used to seed backups.
The process is laid out step by step here: https://helpcenter.veeam.com/backup/vsp ... liary.html
Basically at the source site you create a backup copy job to a local repository. Then copy the backup copy job files to external media. Ship that to your secondary site and move the files to your DR4300 appliance. Rescan the repository on the DR4300 and the files will be found. Edit the backup copy job to use the DR4300 repository and link the job to the new files.