On a computer that is running Windows Vista, Windows 7, or Windows Server 2008 R2, you may be unable to upload a file larger than 7 megabytes (MB) over Transport Layer Security (TLS) 1.0 to a server that is running Internet Information Services (IIS). The issue occurs with non-Microsoft clients only. A network trace between the client and server shows that the IIS TCP window size drops to 0 (zero), and the server cannot recover.
The issue occurs because the HTTP module does not account for the unnecessary 0 bytes buffer. This creates a condition in which HTTP can no longer accept data from the TCP layer. Therefore, the TCP window size drops continuously and does not recover.
To resolve this issue, switch to a later version of TLS.