Why can't I connect to Wi-Fi with my Nokia Lumia 1020?

[UnknownFactor]

So my Nokia Lumia 1020 was upgraded to 8.1 via Preview for Developers a few months ago and Wi-Fi/Cellular data was fine. I updated to Lumia Denim at one time and for some reason, Wi-Fi did not work. I tried using the Windows Phone Recovery Tool 2.1.1 and Wi-Fi still did not work. Then I downgraded from Denim to Cyan, and Wi-Fi still didn't work. I tried the Windows Phone Recovery Tool (same version) again, and Wi-Fi did not work.

In addition, I tried adding my Wi-Fi as a hidden network. Still didn't work. By the way, my Wi-Fi is WPA2-PSK, and I have AES encryption.

So here are some specs of my Lumia 1020 to help with the situation:
OS version: 8.10.14226.359
Firmware revision number: 3051.50009.1451.1001
Model: NOKIA 909
Carrier: AT&T
Software: Windows Phone 8.1 Update

I really don't know if it's really the Wi-Fi itself or the phone itself. Can anybody shed some light on this, please?

 

[pankaj981]

Does your phone connect to other WiFi networks?

 

[UnknownFactor]

I recently connected to another Wi-Fi network, although the connection was open and not secure.

 

[pankaj981]

Interesting. I've seen this when a router does not sign a valid IP address or there is an IP address conflict due to incorrect DHCP assignments. What works in these cases is to either login to your router settings and make sure dynamic DHCP is enabled and/or an IP address is assigned to the phone. Or you can try connecting again immediately after restarting your router.