I was one of the lucky ones like you to upgrade my laptop with the official Windows 10 on the day of release (07/29).
A little icon on the system tray popped up with the message Windows 10 is ready to install when I turned on my laptop in the morning. I wanted to give a try so I went ahead and followed the on screen instruction for the upgrade. The upgrade was very smooth. I didn't even have to take backup. The upgrade utility took care of everything to keep all my personal data and as well the applications installed already.
I was happy to see the new start menu and features in new OS. Even more happy to see all my data after first login. My happiness didn't last longer. When I opened chrome to see how things over the internet. I got the "Unable to connect to Internet". Oh! did I forget to connect to my wifi? Oh No.. I don't see any wifi access points? Oh Hell No.. I don't have an option to set up wireless network.
I was all over the internet looking for solution. Updated the driver quite few times and nothing worked. With the tiring and sad mood, I wanted to get rid of new OS (Windows 10). Luckily Windows 10 had an option to downgrade to previous version of OS i.e. Windows 8.1(The options is available in the Upgrade and Security) section. (Downgrade Windows 10).
Downgrade from windows 10 to 8.1 was smooth again. To my surprise my wifi network configured automatically post downgrade. Voila... This time my internet connection worked in Windows 8.1.
My ego pushed me to upgrade to Windows 10 again. But this time I did little bit home work and research and listed down the possible roadblocks for the network issue in Windows 10.
I came up with the following list- Firewall
- VPN (Virtual Private Network)
Unfortunately I had installed the clients for both firewall (Symantec antivirus) and VPN (Cisco VPN Client). I uninstalled these softwares before attempting to upgrade again. I restarted the windows 8.1 after uninstalling the antivirus and VPN client and upgraded to Windows 10. To my surprise this time I got the wireless network configured automatically and I am connected to my default WIFI router.
Everything works like charm...... I reinstalled the antivirus in Windows 10 and no issues.