Duncan
Sitecom used the N300 designation for a host of different products, range extenders, routers and other wi-fi related stuff. Which doesn't help when you are trying to nail down data.
However if its the WLX-2001 the wall wart included is saId to be 5 volts, 1 amp rating.
Manual here :- **LINK**
http://attachments.content4us.com/datasheets/FULL_MANUAL_CMPSC-WLX2001_ENG.PDF
Odds are that everything in the range using the same basic box will also be 5 volts as there is generally lots of engineering commonality across one makers range.
Always worth doing a Google for the specific manual. Seems that manuals for pretty much anything consumer electrical / electronic and reasonably modern can be found.
Clive