Did you recently install any new software or BIOS updates?
Reboot and immediately press F2 to open BIOS setup. Make sure the onboard NIC is still enabled in BIOS. Be sure to save the change -if any- before exiting setup.
When was last time you replaced motherboard battery? Copy down all current BIOS settings and then power off unplug, and press/hold power button for ~15 sec. Remove the motherboard battery. Press/hold power button for ~30 sec and install a fresh battery. If the battery died, BIOS might not see the NIC.
If you reboot and immediately press F12, you may see an option to run diagnostics so try to run them from there. (Note: This option may have been lost when you downgraded to Win 7.)
The PC probably won't offer a WiFi option as long as the Ethernet cable is connected to rear of PC. So disconnect it from the PC and then launch the Network & Sharing Control Panel and configure your WiFi network connection.
What are you calling the "hub"? Is that your router/modem?
And if all else fails there's always a USB>Ethernet dongle. Plugs into any USB2 or USB3 port on PC and connects the Ethernet cable between the dongle and the router/modem.
Forum Member since 2004
I am not a Dell employee