Broadcom (now owned by Avago/Celestica) removed old Win7 drivers, but you can find them via:
There are hundreds of third-party websites claiming to offer "free driver downloads," but many of these are laden with malware, adware, or broken links. For the safety and stability of your system, you should always source drivers directly from the manufacturer.
If the Windows 7 driver isn't working, try running the installer in Compatibility Mode for Windows Vista. Why the Correct Driver Matters Dell Optiplex 380 Lan Driver Download Windows 7
Installing the official driver ensures stable speeds, proper wake-on-LAN functionality, and reliable data transmission. Technical Specifications for the Dell OptiPlex 380 LAN Broadcom BCM57780 Interface: Integrated 10/100/1000 Mbps Ethernet Compatibility: Windows 7 (32-bit and 64-bit) Driver Type: Network - Ethernet Controller Step-by-Step Download and Installation Guide
You downloaded the 64-bit driver for a 32-bit Windows 7 (or vice versa). Broadcom (now owned by Avago/Celestica) removed old Win7
You can find this file by searching the exact file name on Dell’s FTP archive or trusted driver repositories like DriversCollection.com (but avoid third-party “driver update” junkware).
You can check without installing anything: Why the Correct Driver Matters Installing the official
Manually search for:
You are using a very old Windows 7 RTM version without SHA-2 support.
If you are searching manually or via a search engine, look for these specific file names which were the standard distributions for this