Several months ago I upgraded to MacOS Sierra. As a side effect(bug?) my Sitecom usb-hub, holding 7 ports having it’s own power supply, disappeared from the mac. I searched for the internet for a solution, but there weren’t many answers. Also most of the answers concerned other brand usb-hubs. None of the answers helped my out. If only I read which computer usb ports not to use in combination with by it’s own power supplied usb devices, I wouldn’t have lived with a rather immobile keyboard on my desk that long.