ESXI 10g Network but Win-2008-R2 limited with 1G speed

We recently upgraded all of our vmware esxi 6.5/6.7 servers networks on 10G.

esxi 10g network

All the guests which have windows 2012 or above can transfer data above 1G as shown in below pic.

10G-trasnfer-on-2012-orabove-guests

but on same physical server, all Windows 2008 R2 (64bit with vmware tools installed) related guests vm are limited to 1Gb transfer only as shown in below pic

2008r2 limited to 1g transfer

10g on 2008r2

In 2008R2 guests, I tried to added same Network adapter settings that are on 2012/2016 guests, but no avail. I added different network adapter in w2008r2 vm guest, like VMXNET3 (which shows 10Gb connectivity), VMXNET2 enhanced, and others, but still all 2008R2 guests are not transferring above 1G.

When I perform above testing, I made sure that there should be no other tasks running that can utilize network/disks. So the Vm guests stays idle from network/disk point of view for test purposes.

Is there any tuning that is required ni 2008R2 so that i can utilize 10G bandwidth?