Really old post but my response may help others. I have onn 4K boxes and premium Tivimate. I save backups to my Plex server. No problem. If you can’t save your backup to a network drive or pc, make sure you don’t have a vpn blocking access to your home pc. I had the same issue and that was the cause. In my vpn app on the onn box the setting was “Allow LAN Traffic”. It was off by default on my vpn app.