Are the computers setup dynamically or staticly?...shutting down the firewall sometimes won't do it either...you can set the firewall up to specifically allow the computers acces by the ip address you have assigned the computers...also in your router you can open specific ports....you would have to look into which ones your games likes to use I don't play DW...Google it or these sites may help ya some....
http://www.practicallynetworked.com/...aming_help.htm
http://www.speedguide.net/
Always a good idea ...power down of
ALL devices is a good idea...and restarting in the order of modem/router/computers...try to go back to when the problem began....uninstalling of firewalls and or virus protections is only way sometimes....alot of possibilites....Operating systems etc..."I don't recomend uninstalling any virus protection or firewalls though"...I haven't found a game yet that I could not get going on a lan...except ones that were built bad in the first place for it.