Windows Limited Connectivity (WLAN and LAN)

I was doing some work on a Windows 8.1 laptop for a friend. One of the problems was the WiFi did not work, and he also wanted to upgrade to Windows 10. It would "connect" to the network, but DHCP failed and the machine was never assigned an IP address. The connection was labeled as "Limited" or "Unidentified Network" (depending on where you looked) and the WiFi icon in the task bar had the yellow exclamation point overlay. The same issue (limited connectivity) happened with Ethernet (after plugging in a Cat5 cable).

I proceeded in the following order:

• Uninstall Norton Security (subscription had expired, no longer needed)
• I already had the Windows 10 installation files on a thumb drive, so I went ahead and did the upgrade to Windows 10 (hoping that would magically fix the connectivity issue)

After installing Windows 10, the connectivity issue persisted for both WiFi (WLAN) and Ethernet (LAN). I spent quite a while searching for solutions online and trying various driver configurations. I tried disabling DHCP and assigning an IP address manually. I tried various netsh commands. Nothing seemed to work and I was running out of ideas. I prayed for some divine help (from the omnipotent IT Guy - aka Heavenly Father). I kept trying various things and nothing worked, and I kept praying for help. I finally had the idea inspiration to disable Windows Firewall. And it came to pass ... that the issue was resolved.

Something in Windows Firewall was preventing network connectivity. Just to be certain, I enabled Windows Firewall ... and it broke again. I did not want to leave Windows Firewall off permanently (not a good idea, particular for a laptop that will be used on public networks). From Control Panel's Windows Firewall section, I clicked the "Restore Defaults" link to restore Windows Firewall to its original, default settings. After that, WiFi worked just fine (with Windows Firewall enabled). I cannot say for certain what Windows Firewall settings were causing the problem - but I can confirm that disabling Windows Firewall, and subsequently restoring the default settings, resolved the issue.

I am grateful for the divine inspiration that helped me get this issue resolved.