Two devices cannot ping each other through WiFi

I have WiFi router connected to the Internet through pppoe. Router has latest version of firmware installed. I have no any antivirus software running and firewall enabled.

My router is ASUS RT-N10LX(http://www.asus.com/Networking/RTN10LX/)

My net is   : 192.168.1.0/24  
WiFi gateway: 192.168.1.1  
WiFi clients: 192.168.1.2(OS Windows 7 Professional (x32)),  
              192.168.1.3(Android 4.xx)

I have access to the Internet from any connected devices. I can ping WiFi router from any devices which have wireless connection to it. From webadmin of my WiFi router, I can see IP addresses of all devices connected to it.

I cannot do ping between devices.
I have "Destination Host Unreachable" message.

But I can do ping from my PC if it connected by cable.

I already did:

  i)netsh int ip reset resetlog.txt  
 ii)netsh winsock reset catalog 
iii)netsh -c interface ipv4 add neighbors "Network Card Name" "192.168.1.3" "xx-xx-xx-xx"

What I need to do to resolve this?
__
Thank you in advance for any help.)