Realtek PCIe GBE Family Controller Driver: This is the primary driver for the Ethernet (LAN) port on the back of the desktop.
This guide provides everything you need to find, download, and install the official Dell OptiPlex 3020 network drivers safely and for free. How to Get Dell OptiPlex 3020 Network Drivers for Windows 7
Troubleshooting errors in your Device Manager Realtek PCIe GBE Family Controller Driver: This is
"Hardware Not Found" Error: This usually means you are trying to install a Wi-Fi driver on a machine that only has Ethernet. Check your hardware specs.
Yellow Exclamation Mark: If you see this in Device Manager under "Network Adapters," the driver is missing or corrupt. Check your hardware specs
Manual Selection: If you don't have the tag, select "OptiPlex 3020" from the product list and set your operating system to "Windows 7." Essential Network Drivers for the 3020
Dell Wireless 1540/1506/1705 Driver: Use this if your 3020 is equipped with an internal Wi-Fi card. How to Install Drivers Without an Internet Connection How to Install Drivers Without an Internet Connection
For a standard setup, you will likely need one or both of the following: