Ha... This explains why my 2 years old Netgear router suddenly have update today.
Installed firmware update and reboot... cannot connect to internet. DNS works, the router can connect to outside and my machine can connect to router, just it won't allow any packet route through it.
Run "Reset to default setting", and it can connect to internet. Restore setting from backup and it won't allow me to connect again.
Fine, now I have to type back the settings one by one.... Fxxk.