Yes. You can disconnect, reboot--whatever you need to do. It will pickup where it left off. Performance will be decreased during the encryption process, but should return to near normal after complete. While disconnected the machine won't be able to update its status on the server so until it reconnects after encryption is complete it will continue to show encryption as "In Progress" on the server. Reconnect it to the network at some point after encryption is complete to update the audit trail on the server.