[canadave]

I have a small LAN with a 2008 Macbook Pro and a new 2011 iMac. Both are up to date with Lion, and both connect wirelessly to the network.

On the Macbook Pro, in Finder, I can see the iMac. However, after a while, the iMac disappears. I have to go downstairs and manually wake up the iMac, and then I can see it in Finder again.

Is there something I can do, or set, on the iMac so that it doesn't disappear from Finder when it sleeps?

[Waragainstsleep]

You can stop the iMac from going to sleep under the energy saver preferences in system preferences.

If your wireless LAN is running on Apple Airport equipment, you should be able to implement Wake on WAN. If not, you may not, sorry.