Is it possible to force Windows 10 to use higher TCP window scale

file-transferslow-connectiontcp

I have two Windows 10 machines (bld 2004) I am trying to send data to between two sites. The sites average about 50ms RTT with no packet loss. I am having an issue where the max transfer rate I can achieve is approximately 30Mbps (either direction). Site A is 100Mbps and B is 500Mbps. I have tested using different protocols such as SMB, FTP. IPerf tests confirm the same avg speed. These tests have been performed with the hosts directly attached to the ISP router.

I was told from Network Engineering, that my Window size is too small. Is there any way I can change it to help improve my transfer rate? I was thinking adjusting the TCP window scale size?

https://networkengineering.stackexchange.com/questions/73491/need-help-isolating-bandwidth-issues-between-sites

Best Answer

Microsoft has some detailed information on this:

To set the receive window size to a specific value, add the TcpWindowSize value to the registry subkey specific to your version of Windows. To do so, follow these steps:

Select Start > Run, type Regedit, and then select OK.

Expand the registry subkey specific to your version of Windows:

For Windows 2000, expand the following subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces

For Windows Server 2003, expand the following subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

On the Edit menu, point to New, and then select DWORD Value.

Type TcpWindowSize in the New Value box, and then press Enter

Select Modify on the Edit menu.

Type the desired window size in the Value data box.

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