My wife usually uses her laptop at work with their wireless connection. She has also apparently plugged it in to the LAN connection there a few times. However when she brings it home, unplugs my laptop and plugs hers into our LAN, it does not connect to the internet. My laptop does.

Does a laptop need to be configured somehow to do this ? I can Google the way to do it if someone here would kindly just tell me what the terminology is for doing this...........

Is it something to do with the modem ?

I seem to remember following a few instructions when installing the modem (got True connected 2 months ago)........should I just re-read the modem booklet, maybe ?

Control panel>network connections?

and then choose the Lan connection > properties > ipv4 settings > auto config.

But don't forget to write down the settings there before setting to auto, otherwise she'll have problems connecting at work.

Control panel>network connections?

Your modem may use the MAC (Media Access Controller, not the Apple product) address to "authenticate" to the ISP.

If so, you'll need a router (with multiple ports) that can clone your MAC, faking out the modem. Then you can leave your laptop plugged in and she can plug in and you both can share the internet.

and then choose the Lan connection > properties > ipv4 settings > auto config.

But don't forget to write down the settings there before setting to auto, otherwise she'll have problems connecting at work.

Control panel>network connections?

She uses wireless at work so it is a separate connection not dependent on the LAN settings.

My wife usually uses her laptop at work with their wireless connection. She has also apparently plugged it in to the LAN connection there a few times. However when she brings it home, unplugs my laptop and plugs hers into our LAN, it does not connect to the internet. My laptop does.

Check proxy settings. It's possible your wife's laptop has been configured to use a proxy server at her workplace. If that's the case, you'll have to disable it.