SSLSocket blocks mostly over 3G but works over wifi - ssl

Question

I have a very strange problem regarding networking. I created an andorid app which connects securely to a server running on a PC. Note that though the PC is behind NAT, the respective port has been forwarded. Also PC was placed into DMZ to avoid any port forwarding issue.
The problem is that when I use the code over WIFI, it works perfectly, however, over 3G it almost always (29 out of 30) blocks in the SSLSocket's getOutputStream method (on server side the accept happens).
Can you please assist me what the issue can be?
Thank you
Client code:
E.log("establishing connection: trying to create context");
SSLContext context = SSLContext.getInstance("TLS");
context.init(null, new X509TrustManager[]{new X509TrustManager(){
public void checkClientTrusted(X509Certificate[] chain,
String authType) throws CertificateException {}
public void checkServerTrusted(X509Certificate[] chain,
String authType) throws CertificateException {}
public X509Certificate[] getAcceptedIssuers() {
return new X509Certificate[0];
}}}, new SecureRandom());
E.log("establishing connection: trying to create socket factory");
SSLSocketFactory factory = (SSLSocketFactory) context.getSocketFactory ();
E.log("establishing connection: trying to create socket");
kkSocket = (SSLSocket)
factory.createSocket(host, Integer.parseInt(port));
E.log("establishing connection: trying to create out writer");
out = new PrintWriter(kkSocket.getOutputStream(), true);
E.log("establishing connection: trying to create in reader");
in = new BufferedReader(new InputStreamReader
(kkSocket.getInputStream()));
Failing log:
04-15 00:07:59.066: E/Bubu(17340): starting thread
04-15 00:07:59.076: I/System.out(17340): Mon Apr 15 00:07:59 CEST 2013 - establishing connection: trying to create context
04-15 00:07:59.076: I/System.out(17340): Mon Apr 15 00:07:59 CEST 2013 - establishing connection: trying to create socket factory
04-15 00:07:59.076: I/System.out(17340): Mon Apr 15 00:07:59 CEST 2013 - establishing connection: trying to create socket
04-15 00:07:59.146: D/dalvikvm(17340): GC_CONCURRENT freed 190K, 5% free 7530K/7880K, paused 4ms+2ms, total 23ms
04-15 00:08:01.056: I/System.out(17340): Mon Apr 15 00:08:01 CEST 2013 - establishing connection: trying to create out writer
Success:
04-15 00:13:15.506: E/Bubu(17750): starting thread
04-15 00:13:15.526: I/System.out(17750): Mon Apr 15 00:13:15 CEST 2013 - establishing connection: trying to create context
04-15 00:13:15.536: I/System.out(17750): Mon Apr 15 00:13:15 CEST 2013 - establishing connection: trying to create socket factory
04-15 00:13:15.536: I/System.out(17750): Mon Apr 15 00:13:15 CEST 2013 - establishing connection: trying to create socket
04-15 00:13:15.556: I/System.out(17750): Mon Apr 15 00:13:15 CEST 2013 - establishing connection: trying to create out writer
04-15 00:13:15.746: I/System.out(17750): Mon Apr 15 00:13:15 CEST 2013 - establishing connection: trying to create in reader
04-15 00:13:15.746: I/System.out(17750): Mon Apr 15 00:13:15 CEST 2013 - from server:bubu