diff --git a/include/nuttx/net/iob.h b/include/nuttx/net/iob.h
index 1c0e2b338d..25dbbc39a7 100644
--- a/include/nuttx/net/iob.h
+++ b/include/nuttx/net/iob.h
@@ -304,7 +304,8 @@ int iob_contig(FAR struct iob_s *iob, unsigned int len);
  ****************************************************************************/
 
 #ifdef CONFIG_DEBUG
-void iob_dump(FAR const char *msg, FAR struct iob_s *iob, unsigned int len);
+void iob_dump(FAR const char *msg, FAR struct iob_s *iob, unsigned int len,
+              unsigned int offset);
 #else
 #  define iob_dump(wrb)
 #endif
diff --git a/include/nuttx/net/uip/uip-arch.h b/include/nuttx/net/uip/uip-arch.h
index c6b664d7f7..905af0c507 100644
--- a/include/nuttx/net/uip/uip-arch.h
+++ b/include/nuttx/net/uip/uip-arch.h
@@ -163,7 +163,7 @@ struct uip_driver_s
 
   uint16_t d_len;
 
-  /* When d_buf contains outgoing xmit data, xmtlen is nonzero and represents
+  /* When d_buf contains outgoing xmit data, d_sndlen is nonzero and represents
    * the amount of appllcation data after d_snddata
    */
 
diff --git a/include/nuttx/net/uip/uip-tcp.h b/include/nuttx/net/uip/uip-tcp.h
index f1ccf67dc5..b1e0fac2ff 100644
--- a/include/nuttx/net/uip/uip-tcp.h
+++ b/include/nuttx/net/uip/uip-tcp.h
@@ -139,9 +139,10 @@
   do { (wrb)->wb_iob = iob_trimhead((wrb)->wb_iob,(n)); } while (0)
 
 #ifdef CONFIG_DEBUG
-#  define WRB_DUMP(msg,wrb,len)   tcp_wrbuffer_dump(msg,wrb,len)
+#  define WRB_DUMP(msg,wrb,len,offset) \
+     tcp_wrbuffer_dump(msg,wrb,len,offset)
 #else
-#  define WRB_DUMP(msg,wrb,len)
+#  define WRB_DUMP(msg,wrb,len,offset)
 #endif
 #endif
 
diff --git a/net/iob/iob_dump.c b/net/iob/iob_dump.c
index d767057405..ee7cda4e3a 100644
--- a/net/iob/iob_dump.c
+++ b/net/iob/iob_dump.c
@@ -82,37 +82,68 @@
  *
  ****************************************************************************/
 
-void iob_dump(FAR const char *msg, FAR struct iob_s *iob, unsigned int len)
+void iob_dump(FAR const char *msg, FAR struct iob_s *iob, unsigned int len,
+              unsigned int offset)
 {
+  FAR struct iob_s *head;
   uint8_t data[32];
+  unsigned int maxlen;
   unsigned int nbytes;
-  unsigned int i;
-  unsigned int j;
+  unsigned int lndx;
+  unsigned int cndx;
 
-  message("%s: iob=%p len = %d pktlen=%d\n", msg, iob, len, iob->io_pktlen);
-  len = MIN(len, iob->io_pktlen);
+  head = iob;
+  message("%s: iob=%p pktlen=%d\n", msg, head, head->io_pktlen);
 
-  for (i = 0; i < len; i += 32)
+  /* Check if the offset is beyond the data in the I/O buffer chain */
+
+  if (offset > head->io_pktlen)
     {
-      /* Copy 32-bytes into our local buffer */
+      ndbg("ERROR: offset is past the end of data: %u > %u\n",
+           offset, head->io_pktlen);
+      return;
+    }
 
-      nbytes = iob_copyout(data, iob, 32, i);
+  /* Dump I/O buffer headers */
+
+  for (; iob; iob = iob->io_flink)
+    {
+      message("  iob=%p len=%d offset=%d\n", iob, iob->io_len, iob->io_offset);
+    }
+
+  /* Get the amount of data to be displayed, limited by the amount that we
+   * have beyond the offset.
+   */
+
+  maxlen = head->io_pktlen - offset;
+  len = MIN(len, maxlen);
+
+  /* Then beginning printing with the buffer containing the offset in groups
+   * of 32 bytes.
+   */
+
+  for (lndx = 0; lndx < len; lndx += 32, offset += 32)
+    {
+      /* Copy 32-bytes into our local buffer from the current offset */
+
+      nbytes = iob_copyout(data, head, 32, offset);
 
       /* Make sure that we have something to print */
 
       if (nbytes > 0)
         {
-          message("%04x: ", i);
-          for (j = 0; j < 32; j++)
+          message("  %04x: ", offset);
+
+          for (cndx = 0; cndx < 32; cndx++)
             {
-              if (j == 16)
+              if (cndx == 16)
                 {
                   message(" ");
                 }
 
-              if (i + j < len)
+              if ((lndx + cndx) < len)
                 {
-                  message("%02x", data[j]);
+                  message("%02x", data[cndx]);
                 }
               else
                 {
@@ -121,18 +152,18 @@ void iob_dump(FAR const char *msg, FAR struct iob_s *iob, unsigned int len)
             }
 
           message(" ");
-          for (j = 0; j < 32; j++)
+          for (cndx = 0; cndx < 32; cndx++)
             {
-              if (j == 16)
+              if (cndx == 16)
                 {
                   message(" ");
                 }
 
-              if (i + j < len)
+              if ((lndx + cndx) < len)
                 {
-                  if (data[j] >= 0x20 && data[j] < 0x7f)
+                  if (data[cndx] >= 0x20 && data[cndx] < 0x7f)
                     {
-                      message("%c", data[j]);
+                      message("%c", data[cndx]);
                     }
                   else
                     {
diff --git a/net/net_send_buffered.c b/net/net_send_buffered.c
index 1c75f44db9..639b177ca6 100644
--- a/net/net_send_buffered.c
+++ b/net/net_send_buffered.c
@@ -82,9 +82,9 @@
 #ifdef CONFIG_NET_TCP_WRBUFFER_DUMP
 #  define BUF_DUMP(msg,buf,len) lib_dumpbuffer(msg,buf,len)
 #else
-#  define BUF_DUMP(msg,buf,len)
+#  define BUF_DUMP(msg,buf,len,offset)
 #  undef  WRB_DUMP
-#  define WRB_DUMP(msg,wrb,len)
+#  define WRB_DUMP(msg,wrb,len,offset)
 #endif
 
 /****************************************************************************
@@ -285,12 +285,21 @@ static uint16_t send_interrupt(FAR struct uip_driver_s *dev, FAR void *pvconn,
                    */
 
                   trimlen = ackno - WRB_SEQNO(wrb);
+                  if (trimlen > WRB_SENT(wrb))
+                    {
+                      /* More data has been ACKed then we have sent? */
+
+                      trimlen = WRB_SENT(wrb);
+                    }
+
                   nllvdbg("ACK: wrb=%p trim %u bytes\n", wrb, trimlen);
+
                   WRB_TRIM(wrb, trimlen);
+                  WRB_SEQNO(wrb) = ackno;
+                  WRB_SENT(wrb) -= trimlen;
 
                   /* Set the new sequence number for what remains */
 
-                  WRB_SEQNO(wrb) = ackno;
                   nllvdbg("ACK: wrb=%p seqno=%u pktlen=%u\n",
                           wrb, WRB_SEQNO(wrb), WRB_PKTLEN(wrb));
                 }
@@ -312,7 +321,7 @@ static uint16_t send_interrupt(FAR struct uip_driver_s *dev, FAR void *pvconn,
           nacked = ackno - WRB_SEQNO(wrb);
           if (nacked > WRB_SENT(wrb))
             {
-              /* More data has been ACKed then we have sent? */
+              /* More data has been ACKed then we have sent? ASSERT? */
 
               nacked = WRB_SENT(wrb);
             }
@@ -793,7 +802,7 @@ ssize_t psock_send(FAR struct socket *psock, FAR const void *buf, size_t len,
 
               /* Dump I/O buffer chain */
 
-              WRB_DUMP("I/O buffer chain", wrb, WRB_PKTLEN(wrb));
+              WRB_DUMP("I/O buffer chain", wrb, WRB_PKTLEN(wrb), 0);
 
               /* send_interrupt() will send data in FIFO order from the
                * conn->write_q
diff --git a/net/tcp/tcp.h b/net/tcp/tcp.h
index f855a8044e..c776e7e478 100644
--- a/net/tcp/tcp.h
+++ b/net/tcp/tcp.h
@@ -129,7 +129,8 @@ void tcp_wrbuffer_release(FAR struct tcp_wrbuffer_s *wrb);
 
 #ifdef CONFIG_NET_TCP_WRITE_BUFFERS
 #ifdef CONFIG_DEBUG
-void tcp_wrbuffer_dump(FAR const char *msg, FAR struct tcp_wrbuffer_s *wrb, unsigned int len);
+void tcp_wrbuffer_dump(FAR const char *msg, FAR struct tcp_wrbuffer_s *wrb,
+                       unsigned int len, unsigned int offset);
 #else
 #  define tcp_wrbuffer_dump(msg,wrb)
 #endif
diff --git a/net/tcp/tcp_wrbuffer_dump.c b/net/tcp/tcp_wrbuffer_dump.c
index f91bf20522..6ff5bb0216 100644
--- a/net/tcp/tcp_wrbuffer_dump.c
+++ b/net/tcp/tcp_wrbuffer_dump.c
@@ -80,11 +80,11 @@
  ****************************************************************************/
 
 void tcp_wrbuffer_dump(FAR const char *msg, FAR struct tcp_wrbuffer_s *wrb,
-                       unsigned int len)
+                       unsigned int len, unsigned int offset)
 {
   message("%s: wrb=%p segno=%d sent=%d nrtx=%d\n",
           msg, wrb, WRB_SEQNO(wrb), WRB_SENT(wrb), WRB_NRTX(wrb));
-  iob_dump("I/O Buffer Chain", WRB_IOB(wrb), len);
+  iob_dump("I/O Buffer Chain", WRB_IOB(wrb), len, offset);
 }
 
 #endif /* CONFIG_DEBUG */