Q: I've been using a "Western Digital My Book Live" external hard drive in my home network. But after buying a new wireless router, I can only find the My Book with my wired desktop PC. The drive is invisible to my Wi-Fi laptop.
Here's my setup: I plugged the new router into my existing DSL modem-router, then connected the My Book to the new router. Is it a network address problem? Would it help if I reprogrammed the My Book with a "static" network address that never changes?
Barney Johnson, Minneapolis
A: The disk drive vanished from your laptop because at least one device on your home network has the wrong data address. If you fix that, a larger network overhaul won't be necessary.
Every device on a home network has an Internet Protocol (IP) address. But the "My Book Live" hard drive doesn't come with an IP address. Instead, an address is assigned to it by the network's router, which acts as a data traffic cop.
But your network is a special case because it uses two network routers that are connected to each other. In order for that setup to work, both routers must be assigning the same set of IP addresses. If they don't, that would explain why your laptop can't find the My Book device.
Check your original modem-router to find out what range of IP addresses it assigns to other network devices. Make sure that the new router also assigns IP addresses in that range. In addition, make sure that the new router's own IP address falls within that range, and that its address isn't the same as the address of any other device already in your network.
After that, try connecting your laptop to the My Book by typing "http://mybooklive/UI/" (don't use the quote marks) into the address line of your Web browser. If the My Book has been assigned an appropriate IP address, your laptop should find it.
