Apparently, there's a command:
netsh int ip reset
which resets TCP/IP settings for Windows XP/Vista/7, but I'm not sure that it works correctly on Windows 8.
When I typed the command under command prompt (Admin) I got two errors as pointed out in the screenshot:
Resetting , failed. Access is denied.
At the end it said
Resetting , OK!, so how do I confirm if it worked or not?