In the connections window enter each of these one by one until you get a stable connection. You can also go to Tools>Options>Connections and enter them in the preferences. To see the connections window, you may need to activate it in the view menu.

router.limewire.com
public.bearshare.net
connect1.bearshare.net
connect2.bearshare.net
connect3.bearshare.net
connect1.gnutellanet.com
connect2.gnutellanet.com
connect3.gnutellanet.com
connect4.gnutellanet.com
gnutella.hostscache.com
gnet2.ath.cx
gnotella.fileflash.com
gnet2.ath.cx
gnutella-again.hostscache.com
gnutella.hostscache.com

(not sure all of these are still working)