Ok, I have run iperf3 between my one VM server and Win10 VM and here are the results:
C:\temp>iperf3 -c 192.168.0.86
Connecting to host 192.168.0.86, port 5201
[ 4] local 192.168.0.30 port 52613 connected to 192.168.0.86 port 5201
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-1.00 sec 1.34 GBytes 11.5 Gbits/sec
[ 4] 1.00-2.00 sec 894 MBytes 7.50 Gbits/sec
[ 4] 2.00-3.00 sec 997 MBytes 8.36 Gbits/sec
[ 4] 3.00-4.00 sec 890 MBytes 7.47 Gbits/sec
[ 4] 4.00-5.00 sec 869 MBytes 7.29 Gbits/sec
[ 4] 5.00-6.00 sec 863 MBytes 7.24 Gbits/sec
[ 4] 6.00-7.00 sec 800 MBytes 6.71 Gbits/sec
[ 4] 7.00-8.00 sec 835 MBytes 7.00 Gbits/sec
[ 4] 8.00-9.00 sec 833 MBytes 6.98 Gbits/sec
[ 4] 9.00-10.00 sec 851 MBytes 7.15 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-10.00 sec 8.98 GBytes 7.72 Gbits/sec sender
[ 4] 0.00-10.00 sec 8.98 GBytes 7.72 Gbits/sec receiver
This looks quite good to me??