This a "Connect/receive error". It can also be protocol problem, such as "not enough data sent".
Possible work-arounds / solutions: increase timeout value or number of attempts.
typedef enum BackStatusCode { STATUSCODE_INVALID = -1, STATUSCODE_TIMEOUT = -2, STATUSCODE_SLOW = -3, STATUSCODE_CONNERROR = -4, STATUSCODE_NON_FATAL = -5, STATUSCODE_SSL_HANDSHAKE = -6, STATUSCODE_TOO_BIG = -7, STATUSCODE_TEST_OK = -10 } BackStatusCode;