Client computers No Recent backups

Our server had some HDDs crash and we had to rebuild. I have 98% of all the clients reporting to the new server and backup status for these machines is reporting OK, But I have a handful that act like they cannot see the new server and the backup status on the server is no current backup. I uninstalled the client on one of them and then removed the client from the server and reinstalled the client but still no backup and I don’t see where the client was even recreated on the server.

How do I make sure these client computers can connect to the backup server and do their backups?