For testing tcp performance in Windows we recommend using nttcp tool, From the command line kindly run the NTttcp test and provide the output, the NTttcp tool is provided by Microsoft to test the network performance.
Server side: ntttcp.exe -s -m 8,*,<client ip> -l 128k -a 2 -t 30
Client side: ntttcp.exe -r -m 8,*, <client ip> -l 128k -a 2 -t 30
For your reference kindly see the download and explanation link:
Please let me know about the results.