Rebooting an active server

I’m trying to change the drives that are being backed up with File backups. Defaulted to backing up all the external drives which I don’t want. Changed source backup drives on server, had no effect. Realized I had to change it also on the client. Question is - what’s the proper way to get it restarted properly. Stop button does not seem to do anything. Tempted to reboot. What ill effects would arise when rebooting the server in the middle of a backup. Running on Windows 10.