BlackBerry OS 7.1 encrypted TLS connection closes after a very short time

Summary of the problem : the same client-server configuration, the same network topology, the same device (Bold 9900) - works fine on OS 7.0 , but does not work properly on OS 7.1 , and the secure tls connection is closed by the server after a very short time .

Question . Should there be any difference in opening secure tls between OS 7.0 and OS 7.1? Did RIM change anything in tls infrastructure in 7.1? Is there anything that can cause the tls connection to close prematurely in 7.1?

My application opens a secure tls connection to the server. The connection is supported by a live mechanism for maintaining the application level and remains open until the client closes it. The attached version is a simplified version of the actual code that opens the connection and reads from the socket. The code works fine on OS 5.0-7.0, but does not work properly on OS 7.1.

When working in OS 7.1, the lock read()returns from -1 (the end of the stream is reached) after a very short time (10-45 seconds). For OS 5.0-7.0, the call read()remains blocked until the following data appears and the connection is never closed by the server.

Connection connection = Connector.open(connectionString);
connInputStream = connection.openInputStream();
while (true) {
    try {
        retVal = connInputStream.read();
        if (-1 == retVal) {
            break;   // end of stream has been reached
        }

    } catch (Exception e ) {
        // do error handling
    }

    // data read from stream is handled here
}

1:
-, , tls ( WiFi) 7.1. , , OS 7.1.

tls :

connectionString = "tls://someipaddress:443;deviceside=false;ConnectionType=mds-**secret**;EndToEndDesired";

tls Wifi :

connectionString = "tls://someipaddress:443;interface=wifi;EndToEndRequired"

2:
. . WiFi. OS 7.1, . , - , tls.

3:
Wireshark, OS 7.1, tls ( FIN). , tls, , -, ts handshake.

4:
tls , RSA 2048 AES 256 OS 7.1. OS 7.0. , DHE/DSS 768 AES 128 7.1, . - RSA 2048 AES 256 suite.ideas?