...had similar issues with all of my wifi-connected Linux laptops - ie Internet access working fine, but pinging a wifi connected laptop from another wifi-connected laptop not working with the command line reporting "Destination Host Unreachable". In m cas it was how the router handles wifi connections. The CIsco "Help" says: "AP Isolation creates a separate virtual network for your wireless network. When this feature is enabled, each of your wireless clients will be in its own virtual network and will not be able to communicate with each other. You may want to enable this feature if you have many guests that frequent your wireless network. The default setting is Disable." So in my case "AP Isolation" needed disabling. But here's a gotcha... It was showing already showing disabled in the router settings and I had to enable and re-disable it - it then took about a minute for the router to execute the setting. I tried the whole process several time and sure enough with AP Isolation disabled all is accessible. If you do this, watch out for next door rummaging around on your file system though!