lose net connection when waking from sleep (dually 867 and linksys router)

The dually works fine, but when it wakes from sleep it won't connect to the net. I have to unplug the router and plug it back in.
Gary Jaz wrote on :

I have a dually 867 (10.2.8) and a cable modem which has run fine for months. I just got a wireless linksys router BEFW11S4 ver. 4. I don't have a wireless card for the dually so it's connected to the router with a cat 5 cable. My laptop connects to the router fine witha wireless card. The dually works fine, but when it wakes from sleep it won't connect to the net. I have to unplug the router and plug it back in. I open the network pane and switch to manual ip settings, apply it, then switch back to dhcp and apply. Then it works.

This is quite a hassle. What can I do to fix things so the mac can connect to the net when waking from sleep?

--jaz