What router are you using? and what's your OS?
change the ip address seen above (value: 192.168.15.4)to this: 192.168.15.143
That did not work.
I don't believe you.
Follow step 3 from here, redo the settings, and disable your firewall.
for the ips you put in on step 3 as stated above..192.168.15.143255.255.255.0192.168.15.40