libsoup often fails with SOUP_STATUS_IO_ERROR

[LRN <lrn1986 gmail com>]

 libsoup returns error (status_code == SOUP_STATUS_IO_ERROR; 
reason_phrase == "Connection terminated unexpectedly" ) to callback 
function. I tried both libsoup 2.4 and 2.23 - no effect.
Wireshark shows that SYN - SYN, ACK, ACK sequence is present, but 
instead of sending actual HTTP GET request libsoup just starts FIN, ACK 
- FIN, ACK, ACK sequence.
This behaviour is not consistent. Sometimes it connects and request 
passes by, but most of the time it doesn't.
OS is NT v5.02.