I recently moved from my old Windows 10 PC to a new one with Windows 11. Both computers had/have a number of external drives connected through a USB hub.

When I run a backup from one of the external disks to another one all goes well for some time, but then the destination disk seems to get disconnected, and I begin to get "A device which does not exist was specified" errors. The disk isn't accessible until I reboot.
I've never had this problem with my Win10 PC.

Any idea what causes this, and how to solve it? I've seen suggestions ranging from rebooting to replacing the hard disk. Needless to say that neither are satisfying.

Disks: WD Elements
USB hub: Anker USB 3.1
Backup software: SyncbackSE

(edit: more details, upon request from Robert):
MB chipset: Intel Tiger Point B560, Intel Comet Lake-S
CPU: Intel Core i5-10400
USB: Intel USB 3.20 eXtensible Host Controller - 1.20 (Microsoft)