Hi,
Short version: Hyper-V role installed on Windows 2019 with gen2 Win 2019 VM. File share created on that Win 2019 VM. File open (200Mb) or copy from share with Win 10 client machine is realy slow.
Please check detailed issue description: https://social.msdn.microsoft.com/Forums/en-US/3248a691-d32f-4ac6-9175-94524afc35ba/windows-server-2019-hyperv-guest-on-windows-server-2019-hyperv-host-networking-performance-error?forum=servervirtualization .
I guess we have posted it on the wrong place..