I have a Windows 11 PC with an Intel I226-V NIC that is 2.5G and I loaded your experimental firmware and bought an ipolex 1.25/2.5/5/10G SFP+ RJ45 Copper Transceiver, 10GBase-T RJ-45 SFP+ Module, put it in my RT-AX89X set the port to 2.5G and it works perfectly and is lightning fast.