The AC3 has exactly the same switch chip Atheros8327. And I have exactly the same problem. I have connected a Netis 5 gigabit port switch between router and PC2. Connection = 1 gigabit. I also tested the D-link on port 24. Connection = 1 gigabit. Let's hope that in five years the problem will be cor...

A similar problem. old PC1: has a gigabit Ethernet port new PC2: on the motherboard gigabit z590 aurus master has a 10 gigabit Ethernet port (AQC107) router: hAP AC3 pc1 is connected to the router with a cable.(router-cable-pc1). Connection = 1 gigabit. I take this cable out of the network connector...