Can't access internet Suddenly, a couple of days ago, I have started to have major problems accessing internet through my home network, with my MacBook Pro Mid 2012 (non-retina) running Mountain Lion. 

I connect to the network just fine, but when can't open web pages or when I try to ping google.com I get:

ping: cannot resolve google.com: Unknown host


or something like:

PING google.com (173.194.32.33): 56 data bytes
Request timeout for icmp_seq 0
64 bytes from 173.194.32.33: icmp_seq=1 ttl=53 time=43.372 ms
Request timeout for icmp_seq 2
Request timeout for icmp_seq 3
Request timeout for icmp_seq 4
64 bytes from 173.194.32.33: icmp_seq=5 ttl=53 time=45.110 ms

--- google.com ping statistics ---
6 packets transmitted, 2 packets received, 66.7% packet loss
round-trip min/avg/max/stddev = 43.372/44.241/45.110/0.869 ms


I can't find any pattern to the results.

ALL other devices on the router has no problem access neither the network or internet. Of these are another MacBook Pro, an iPad, several iPhones, Apple TV, and misc.

The network is set up to configure IPv4 with DHCP and IPv6 automatically. (Under General > Network Wi-Fi > Advanced > TCP/IP)

I have tried flushing the DNS with both: (https://gist.github.com/mipmip/1844353)

sudo killall -INFO mDNSResponder
----------------------------------------------------------------------------------
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist


I have tried removing and adding the Wi-Fi interface from General > Network.

And of course I have tried rebooting the modem, router and computer.

What else should I do to get internet working again?
Delete the following 3 files located in ~Library &gt; Preferences &gt; SystemConfiguration :


 com.apple.airport.preferences.plist
 com.apple.network.identification.plist
 NetworkInterfaces.plist


Delete the airport / wifi network interface and re-create.
Reboot and connect to WiFi