post-upgrade and reboot is mandatory after a restore.
only the services configured on initial boot are ready to start with the systemd sequence and the one added during the restore are not seen.
more over all your restored configuration and eventually modifications with console needs this reboot.
That's good to know, thanks. One question though. I used the server manager backup to transfer everything to the new SME10 server, but at some point I lost connection to the server (for the reasons you and reetp have outlined above). How am I supposed to know when the restore is complete and it is safe to do the reconfigure and reboot?
In my case I noted the time it had taken for a full backup on the old server, then when I did the restore I waited for a full hour longer before reconfiguring and rebooting the new server (I also noted that the light on the USB backup drive had stopped flashing some time before).
Is there another way? Thank you.