There is a difference in the way backups are stored if they are on network drive as opposed to a local external drive.
Read Pondini about how to move backups between the two type.
Thanks LaPastenague. I tried this, but unfortunately my backup was too big and something wasn't consistant so Time Machine wanted a brand new backup. But this link was really helpful to understand a lot of things and now I am running two sets of backups, once using Time Machine and the other via rsync.