I changed it with a new RSHTech 7-port USB hub, and the black-monitor reboots proceed. I'm stumped at this time, essentially beginning to suspect my UPS of spikes or momentary cutouts. Anyway I think the Sabrent is https://reganhomb302395.creacionblog.com/28389941/the-2-minute-rule-for-qvs-usb-3-1-gen-1-type-a-male-to-usb-3-1-gen-1-type-c-female-adapter