I bought a TP Link Omada ER707-M2 with this switch, and I put a TP-Link 2.5GB PCIe NIC in my PC. I get 1800Mbps (I have a 1.5Gb line).
Any of my gigabit devices plugged into the switch gets only 50Mbps.
Why? Is the switch bad? Even though it’s backwards compatible.
I would always verify the cables first. A faulty or improper cable can do strange things to speed negotiations. I seriously doubt that you are working with long cable rubs, but that can cause issues too.
See if you can turn off auto negotiation and force your devices to 1000 or higher. That may give you some more information to work with.
So I downloaded the beta firmware for the router, which enables flow control. As soon as I enabled it, it worked great with devices directly connected to the router. As soon as I plug in the unmanaged switch, it goes right back to 1800Mbps on 2.5 NIC PC, and 50-100Mbps on the gigabit NIC PC.
Now I am wondering, even though they are unmanaged switches, are they somehow interfering? I mean obviously there was an issue before, but the flow control fixed it until the switches were involved again.