I try to use two external USB 3 2.5 inch hard drives (same make/model) attached to an active USB 3 hub with 4 ports. It is a single board computer with only one USB port. One drive gets recognized, the other spins up and is then somehow put to sleep. Dmesg/lsusb only shows one connected drive. Both drives are functional when connected as only device on the USB hub. Both drives work on another PC.
Is there a limit on the number of hard drives that may be attached to a single port? The USB hub features 900mA per port.
How do I make it work?