When using TLS 1.x, the .NET Framework relies on the underlying Windows SCHANNEL API. Starting with .NET Framework 4.6, the [`SCH_SEND_AUX_RECORD`](https://msdn.microsoft.com/library/windows/desktop/aa379810.aspx) flag is passed by default to SCHANNEL. This causes SCHANNEL to split data to be encrypted into two separate records, the first as a single byte and the second as *n*-1 bytes.
If this change breaks communication with an existing server, you can disable sending the [`SCH_SEND_AUX_RECORD`](https://msdn.microsoft.com/library/windows/desktop/aa379810.aspx) flag and restore the previous behavior of not splitting data into separate records by adding the following switch to the [`<AppContextSwitchOverrides>`](~/docs/framework/configure-apps/file-schema/runtime/appcontextswitchoverrides-element.md) element in the [`<runtime>`](~/docs/framework/configure-apps/file-schema/runtime/runtime-element.md) section of your app configuration file: