Q When working at another office, my MacBook had run out of free USB ports, so I connected it to a printer through a cheap USB hub. When I returned from lunch to wake the MacBook up, the printer was no longer recognised. Which was at fault – my Mac, or the printer?

A Most probably neither, but the culprit is likely to have been your USB hub.

For hubs to support waking after sleep properly, and restore their USB connections, they need to follow a standard USB wakeup sequence. Some hubs do not support that correctly, in which case they may lose connectivity with printers, storage devices such as hard disks which can thus result in data loss, or external mice or keyboards.

Comments The first choice is to connect all USB devices direct to a USB port on your Mac, or through the USB ports on an Apple display that is in turn connected direct to a port on your Mac.

If you must use a hub, ensure that it supports the wakeup sequence properly. Sometimes you can work around issues with waking up by pressing the power button on a Mac instead of trying to wake it using an input device that is connected to a hub.

Updated from the original, which was first published in MacUser volume 27 issue 10, 2011.