A USB hub is a great way of giving your PC or laptop additional USB ports. But USB hubs aren't great at powering up your gadgets. Our Helproom Editor explains why your USB hub may not be charging your smartphone or external hard drive, and how you can solve that problem.

QUESTION My laptop has three USB ports, but this isn't enough to cater for my two external hard drives, a mouse, a USB flash drive and an external USB keyboard. Sometimes I also attach my phone via USB to use as a modem. I've invested in a four-port USB hub, with which the keyboard, mouse and USB flash drive work fine, but not the external hard drives or phone. What can I do to fix the problem?

HELPROOM ANSWER This issue is almost certainly down to the amount of power required by your USB devices. Portable external hard drives require significantly more power than a USB flash drive or keyboard, and this power has to come from the USB port.

To ensure these peripherals work correctly, you'll need to use a powered hub. This comes with an external power supply that you plug into the mains. Many hubs come without power supplies, but have a socket for you to attach one later. Have a look and see if this is the case with your hub – you may be able to buy a power supply rather than another hub.

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USB hub