I have been able to connect to my Sentinel and do Time Machine Backups from Mavericks by doing the following:
Connect to the Sentinel in finder using the IP (AFP) connection. I then mount the Time Machine Folder.
After this I start the backup in time machine and it finds the server okay.
Successive backups seem to work fine, ie this was just needed on the first connection for me.
Also I noted that this was for clean installs of Mavericks. Upgraded machines that were already backing up to the Sentinel were fine.
Andrew
