The Realtek PCIe Ethernet controller repeatedly restarts at 100Mbps.
The Realtek PCIe Ethernet controller repeatedly restarts at 100Mbps.
I own an older Dell 3020 that functions as both an Emby server and a PiHole server. I've encountered a persistent problem where the built-in Realtek Ethernet controller switches back to 100Mbps from its 1Gbps capacity when I don't remotely adjust the machine. Many users report similar issues, so I've turned off all power-saving settings, forcing the card to only accept 1Gbps rather than auto-negotiating. However, these fixes only provide temporary relief. Since this device is my PiHole server and I have a 500Mbps connection, when it drops to 100Mbps, my internet speed effectively falls below 100Mbps as well. I'm looking for a lasting solution to this matter.
Verify Dell's BIOS settings for any power-saving networking options. Inspect the ethernet cable for damage or improper connections; replace if necessary. Consider using a different cable to confirm functionality. Also, check if any "green" network switches upstream from the server are affecting performance.