I have a Dir 628,,,    Wanted to control my wireless laptop on my local private network (192.168.x.x) from my wired PC desktop.. I found that I cannot ping the wireless local address , 192.168.0.190 from my wired desktop 192.168.0.197..  If I put a wired connection to the laptop, this then works ok.. I'm running Norton from Comcast for my virus protection..  
The web contains a few of this exact symptoms, different wireless routers, but no real fixes.. 
Think this has something to do with the 802 wireless security somewhere..