diff --git a/fnet_doc/doxygen/fnet_doc.dox b/fnet_doc/doxygen/fnet_doc.dox
index d5086109..258b6502 100644
--- a/fnet_doc/doxygen/fnet_doc.dox
+++ b/fnet_doc/doxygen/fnet_doc.dox
@@ -2361,6 +2361,10 @@ Press any key to continue . . .
 
 FNET public releases:
 
+- Version 4.7.1
+    - Broadcast a DHCP DECLINE message, instead of unicasting.
+    - Randomize TCP initial sequence number.
+
 - Version 4.7.0
 	- Fix possible out of bounds read on a received malformed LLMNR, mDNS or IPv6 packet.
 	- Add null termination check for the input-name parameter of the LLMNR, mDNS and DNS services.
diff --git a/fnet_doc/doxygen/fnet_gen_doc.in b/fnet_doc/doxygen/fnet_gen_doc.in
index e8abc875..65feea52 100644
--- a/fnet_doc/doxygen/fnet_gen_doc.in
+++ b/fnet_doc/doxygen/fnet_gen_doc.in
@@ -38,7 +38,7 @@ PROJECT_NAME           = "Embedded TCP/IP stack"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 4.7.0
+PROJECT_NUMBER         = 4.7.1
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/fnet_doc/doxygen/fnet_gen_doc_chm.in b/fnet_doc/doxygen/fnet_gen_doc_chm.in
index 912ab256..01dfb3b6 100644
--- a/fnet_doc/doxygen/fnet_gen_doc_chm.in
+++ b/fnet_doc/doxygen/fnet_gen_doc_chm.in
@@ -38,7 +38,7 @@ PROJECT_NAME           = "Embedded TCP/IP stack"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 4.7.0
+PROJECT_NUMBER         = 4.7.1
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/fnet_doc/fnet_user_manual.chm b/fnet_doc/fnet_user_manual.chm
index 651fc321..c8492812 100644
Binary files a/fnet_doc/fnet_user_manual.chm and b/fnet_doc/fnet_user_manual.chm differ
diff --git a/fnet_stack/fnet.h b/fnet_stack/fnet.h
index e35b375c..538579ca 100644
--- a/fnet_stack/fnet.h
+++ b/fnet_stack/fnet.h
@@ -73,7 +73,7 @@
  *        string.
  * @showinitializer
  ******************************************************************************/
-#define FNET_VERSION            "4.7.0"
+#define FNET_VERSION            "4.7.1"
 
 /*! @} */
 
diff --git a/fnet_stack/service/dhcp/fnet_dhcp_cln.c b/fnet_stack/service/dhcp/fnet_dhcp_cln.c
index be9bcead..5d558a43 100644
--- a/fnet_stack/service/dhcp/fnet_dhcp_cln.c
+++ b/fnet_stack/service/dhcp/fnet_dhcp_cln.c
@@ -475,7 +475,7 @@ static void _fnet_dhcp_cln_send_message( fnet_dhcp_cln_if_t *dhcp )
             message_type = FNET_DHCP_OPTION_MSG_TYPE_REQUEST;
             break;
         case FNET_DHCP_CLN_STATE_PROBING:
-            ip_address = dhcp->current_options.public_options.dhcp_server; /* Send REQUEST to leasing server*/
+            ip_address.s_addr = INADDR_BROADCAST; /* As the client does not have a valid network address, the client must broadcast the DHCPDECLINE message. */
             message->header.ciaddr = dhcp->current_options.public_options.ip_address.s_addr;
             message_type = FNET_DHCP_OPTION_MSG_TYPE_DECLINE; /* DHCPDECLINE - Client to server indicating network address is already in use.*/
             break;
diff --git a/fnet_stack/stack/fnet_tcp.c b/fnet_stack/stack/fnet_tcp.c
index e093f090..29ec88d8 100644
--- a/fnet_stack/stack/fnet_tcp.c
+++ b/fnet_stack/stack/fnet_tcp.c
@@ -110,6 +110,7 @@ static fnet_return_t _fnet_tcp_setsockopt( fnet_socket_if_t *sk, fnet_protocol_t
 static fnet_return_t _fnet_tcp_getsockopt( fnet_socket_if_t *sk, fnet_protocol_t level, fnet_socket_options_t optname, void *optval, fnet_size_t *optlen );
 static fnet_return_t _fnet_tcp_listen( fnet_socket_if_t *sk, fnet_size_t backlog );
 static void _fnet_tcp_drain( void );
+static void _fnet_tcp_initial_seq_number_update( void );
 
 #if FNET_CFG_DEBUG_TRACE_TCP && FNET_CFG_DEBUG_TRACE
     void _fnet_tcp_trace(fnet_uint8_t *str, fnet_tcp_header_t *tcp_hdr);
@@ -127,8 +128,8 @@ static void _fnet_tcp_drain( void );
 /* Initial Sequence Number
  * tcpcb_isntime is changed by STEPISN every 0.5 sec.
  * Additionaly, each time a connection is established,
- * tcpcb_isntime is also incremented by FNET_TCP_INITIAL_SEQ_NUMBER_STEP */
-static fnet_uint32_t _fnet_tcp_initial_seq_number = 1u;
+ * tcpcb_isntime is also incremented by FNET_TCP_INITIAL_SEQ_NUMBER_STEP + random value */
+static fnet_uint32_t _fnet_tcp_initial_seq_number;
 
 /* Timers.*/
 static fnet_timer_desc_t fnet_tcp_fasttimer;
@@ -174,7 +175,7 @@ fnet_prot_if_t fnet_tcp_prot_if =
 *************************************************************************/
 static fnet_return_t _fnet_tcp_init( void )
 {
-    /* Create the slow timer.*/
+    /* Create the fast timer.*/
     fnet_tcp_fasttimer = _fnet_timer_new(FNET_TCP_FAST_TIMER_PERIOD_MS, _fnet_tcp_fasttimo, 0u);
 
     if(!fnet_tcp_fasttimer)
@@ -182,7 +183,7 @@ static fnet_return_t _fnet_tcp_init( void )
         return FNET_ERR;
     }
 
-    /* Create the fast timer.*/
+    /* Create the slow timer.*/
     fnet_tcp_slowtimer = _fnet_timer_new(FNET_TCP_SLOW_TIMER_PERIOD_MS, _fnet_tcp_slowtimo, 0u);
 
     if(!fnet_tcp_slowtimer)
@@ -192,6 +193,9 @@ static fnet_return_t _fnet_tcp_init( void )
         return FNET_ERR;
     }
 
+    /* Initialize ISN */
+    _fnet_tcp_initial_seq_number_update();
+
     return FNET_OK;
 }
 
@@ -437,6 +441,14 @@ static fnet_return_t _fnet_tcp_attach( fnet_socket_if_t *sk )
     return FNET_OK;
 }
 
+/************************************************************************
+* DESCRIPTION: This function updates TCP ISN.
+*************************************************************************/
+static void _fnet_tcp_initial_seq_number_update( void )
+{
+    /* Increase Initial Sequence Number. */
+    _fnet_tcp_initial_seq_number += FNET_TCP_INITIAL_SEQ_NUMBER_STEP + fnet_rand() & 0xFF;
+}
 /************************************************************************
 * DESCRIPTION: This function performs the connection termination.
 *
@@ -591,7 +603,7 @@ static fnet_return_t _fnet_tcp_connect( fnet_socket_if_t *sk, struct fnet_sockad
     sk->state = SS_CONNECTING;
 
     /* Increase Initial Sequence Number.*/
-    _fnet_tcp_initial_seq_number += FNET_TCP_INITIAL_SEQ_NUMBER_STEP;
+    _fnet_tcp_initial_seq_number_update();
 
     /* Initialize Abort Timer.*/
     cb->tcpcb_timers.retransmission = cb->tcpcb_rto;
@@ -1790,7 +1802,7 @@ static fnet_bool_t _fnet_tcp_inputsk( fnet_socket_if_t *sk, fnet_netbuf_t *inseg
             _fnet_tcp_send_headseg(psk, FNET_TCP_SGT_SYN | FNET_TCP_SGT_ACK, options, optionlen);
 
             /* Increase ISN (Initial Sequence Number).*/
-            _fnet_tcp_initial_seq_number += FNET_TCP_INITIAL_SEQ_NUMBER_STEP;
+           _fnet_tcp_initial_seq_number_update();
 
             /* Initialization the connection timer.*/
             pcb->tcpcb_timers.connection = FNET_TCP_ABORT_INTERVAL_CON;
@@ -2745,7 +2757,7 @@ static void _fnet_tcp_slowtimo(fnet_uint32_t cookie)
         sk = nextsk;
     }
 
-    _fnet_tcp_initial_seq_number += FNET_TCP_INITIAL_SEQ_NUMBER_STEP;
+    _fnet_tcp_initial_seq_number_update();
 
     fnet_isr_unlock();
 }
diff --git a/readme.txt b/readme.txt
index e052e5df..0d8014da 100644
--- a/readme.txt
+++ b/readme.txt
@@ -17,7 +17,7 @@ The stack provides following protocols and services:
 		- QCA4002 (GT202-GC3013-FRDM4-KIT board).
 		- QCA4004 (SX-ULPAN-2401-SHIELD board). 
 - Supported Compilers:
-	- IAR: Embedded Workbench for ARM, version 8.50
+	- IAR: Embedded Workbench for ARM, version 8.22
 	- GCC: Kinetis Design Studio, version 3.2 
 - Bare-metal TCP/IP stack. No underlying RTOS is required, although it can be used with it. FreeRTOS example is provided.
 - Certified logos for: