Recently a friend of mine had a problem with his new Dell laptop upgraded to Windows 10 x64; the OS seems to connect to the LAN via wifi nic, it reaches the default gateway but no web browsing and ping on a reachable host (for example www.google.com) returned “general failure error”

DNS resolution OK
Routing table clear
No blocking firewall or security application
No suspect malware or anything strange on software
No hardware problem (checked with a live GNU/Linux distro)
No network problem with other devices
No useful trace on event log

It seems the Windows network stack went crazy so I tried to reset it to default parameters.
Start command prompt with administrative rights and launch:

• netsh winsock reset catalog

  for reset WINSOCK entries to installation defaults.

• netsh int ipv4 reset

  for reset IPv4 TCP/IP stack to installation defaults.

• netsh int ipv6 reset

  for reset IPv6 TCP/IP stack to installation defaults.

• restart

Problem fixed ;)