Q. What speed to synthetic NICs in Hyper-V 2016 see?
A. Unlike vmNICs on VM hosts prior to Windows Server 2016 which saw a set speed, vmNICs on Windows Server 2016 or above Hyper-V hosts see the actual connected speed of the NICs servicing the vSwitch. As an example a vSwitch connected to two 10 Gbps NICs would show as a speed of 20 Gbps on the vmNIC. Note any QoS restrictions are not considered in the speed shown to the VM and as with previous versions this is no guarantee of that actual speed and some traffic such as VM to VM on same host will never even touch the physical NICs.