diff --git a/net/tcp/tcp.h b/net/tcp/tcp.h
index c11550d742..78147ed352 100644
--- a/net/tcp/tcp.h
+++ b/net/tcp/tcp.h
@@ -175,10 +175,7 @@ struct tcp_conn_s
   uint8_t  rcvseq[4];     /* The sequence number that we expect to
                            * receive next */
   uint8_t  sndseq[4];     /* The sequence number that was last sent by us */
-#if !defined(CONFIG_NET_TCP_WRITE_BUFFERS) || \
-    defined(CONFIG_NET_SENDFILE)
   uint32_t rexmit_seq;    /* The sequence number to be retrasmitted */
-#endif
   uint8_t  crefs;         /* Reference counts on this instance */
 #if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6)
   uint8_t  domain;        /* IP domain: PF_INET or PF_INET6 */
diff --git a/net/tcp/tcp_appsend.c b/net/tcp/tcp_appsend.c
index 1e8e58dbc2..39b120f3d8 100644
--- a/net/tcp/tcp_appsend.c
+++ b/net/tcp/tcp_appsend.c
@@ -322,30 +322,23 @@ void tcp_rexmit(FAR struct net_driver_s *dev, FAR struct tcp_conn_s *conn,
    * new data in it, we must send out a packet.
    */
 
-#if defined(CONFIG_NET_TCP_WRITE_BUFFERS) && defined(CONFIG_NET_SENDFILE)
-  if (conn->sendfile)
-#endif
+  if ((result & TCP_REXMIT) != 0 &&
+      dev->d_sndlen > 0 && conn->tx_unacked > 0)
     {
-#if !defined(CONFIG_NET_TCP_WRITE_BUFFERS) || defined(CONFIG_NET_SENDFILE)
-      if ((result & TCP_REXMIT) != 0 &&
-          dev->d_sndlen > 0 && conn->tx_unacked > 0)
-        {
-          uint32_t saveseq;
+      uint32_t saveseq;
 
-          /* According to RFC 6298 (5.4), retransmit the earliest segment
-           * that has not been acknowledged by the TCP receiver.
-           */
+      /* According to RFC 6298 (5.4), retransmit the earliest segment
+       * that has not been acknowledged by the TCP receiver.
+       */
 
-          saveseq = tcp_getsequence(conn->sndseq);
-          tcp_setsequence(conn->sndseq, conn->rexmit_seq);
+      saveseq = tcp_getsequence(conn->sndseq);
+      tcp_setsequence(conn->sndseq, conn->rexmit_seq);
 
-          tcp_send(dev, conn, TCP_ACK | TCP_PSH, dev->d_sndlen + hdrlen);
+      tcp_send(dev, conn, TCP_ACK | TCP_PSH, dev->d_sndlen + hdrlen);
 
-          tcp_setsequence(conn->sndseq, saveseq);
+      tcp_setsequence(conn->sndseq, saveseq);
 
-          return;
-        }
-#endif
+      return;
     }
 
 #if defined(CONFIG_NET_TCP_WRITE_BUFFERS)
diff --git a/net/tcp/tcp_send_buffered.c b/net/tcp/tcp_send_buffered.c
index c5aac33db8..d00962c8ae 100644
--- a/net/tcp/tcp_send_buffered.c
+++ b/net/tcp/tcp_send_buffered.c
@@ -323,7 +323,9 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
    */
 
   FAR struct tcp_conn_s *conn = pvpriv;
-  bool rexmit = false;
+#ifdef CONFIG_NET_TCP_FAST_RETRANSMIT
+  uint32_t rexmitno = 0;
+#endif
 
   /* Get the TCP connection pointer reliably from
    * the corresponding TCP socket.
@@ -501,12 +503,9 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
                 {
                   /* Do fast retransmit */
 
-                  rexmit = true;
-                }
-              else if ((TCP_WBNACK(wrb) > TCP_FAST_RETRANSMISSION_THRESH) &&
-                       TCP_WBNACK(wrb) == sq_count(&conn->unacked_q) - 1)
-                {
-                  /* Reset the duplicate ack counter */
+                  rexmitno = ackno;
+
+                  /* Reset counter */
 
                   TCP_WBNACK(wrb) = 0;
                 }
@@ -573,14 +572,77 @@ static uint16_t psock_send_eventhandler(FAR struct net_driver_s *dev,
       return flags;
     }
 
+#ifdef CONFIG_NET_TCP_FAST_RETRANSMIT
+  if (rexmitno != 0)
+    {
+      FAR struct tcp_wrbuffer_s *wrb;
+      FAR sq_entry_t *entry;
+      FAR sq_entry_t *next;
+      size_t sndlen;
+
+      /* According to RFC 6298 (5.4), retransmit the earliest segment
+       * that has not been acknowledged by the TCP receiver.
+       */
+
+      for (entry = sq_peek(&conn->unacked_q); entry; entry = next)
+        {
+          wrb = (FAR struct tcp_wrbuffer_s *)entry;
+          next = sq_next(entry);
+
+          if (rexmitno != TCP_WBSEQNO(wrb))
+            {
+              continue;
+            }
+
+          conn->rexmit_seq = rexmitno;
+
+          /* Reconstruct the length of the earliest segment to be
+           * retransmitted.
+           */
+
+          sndlen = TCP_WBPKTLEN(wrb);
+
+          if (sndlen > conn->mss)
+            {
+              sndlen = conn->mss;
+            }
+
+          /* As we are retransmitting, the sequence number is expected
+           * already set for this write buffer.
+           */
+
+          DEBUGASSERT(TCP_WBSEQNO(wrb) != (unsigned)-1);
+          conn->rexmit_seq = TCP_WBSEQNO(wrb);
+
+#ifdef NEED_IPDOMAIN_SUPPORT
+          /* If both IPv4 and IPv6 support are enabled, then we will need to
+           * select which one to use when generating the outgoing packet.
+           * If only one domain is selected, then the setup is already in
+           * place and we need do nothing.
+           */
+
+          send_ipselect(dev, conn);
+#endif
+          /* Then set-up to send that amount of data. (this won't actually
+           * happen until the polling cycle completes).
+           */
+
+          devif_iob_send(dev, TCP_WBIOB(wrb), sndlen, 0);
+
+          /* Reset the retransmission timer. */
+
+          tcp_update_retrantimer(conn, conn->rto);
+
+          /* Continue waiting */
+
+          return flags;
+        }
+    }
+#endif
+
   /* Check if we are being asked to retransmit data */
 
-  else if ((flags & TCP_REXMIT) != 0)
-    {
-      rexmit = true;
-    }
-
-  if (rexmit)
+  if ((flags & TCP_REXMIT) != 0)
     {
       FAR struct tcp_wrbuffer_s *wrb;
       FAR sq_entry_t *entry;