I should probably also post a link to the online manual for the router. Unfortunately I've read the section on QoS over and over but it means very little to me because I don't really understand the terminology used!
ftp://ftp.zyxel.co.uk/VMG8324-B10A/u...8324-B10A_.pdf
ftp://ftp.zyxel.co.uk/VMG8324-B10A/u...8324-B10A_.pdf