To see if it's hardware, try some USB or Ethernet Wifi-dongle.
To see if it's hardware, try WiFi after booting from a Linux disk (not guaranteed to work without drivers)
To see if it's related to the router, try WiFi at another location (friend, family member, public hotspot).
To see if it's software or settings, try going back to factory conditions. Make an image backup before you do, so you can easily go back to the current situation if it makes no difference at all.