diff --git a/ChangeLog b/ChangeLog
index 2bda7e474b..cc6e9cd57a 100755
--- a/ChangeLog
+++ b/ChangeLog
@@ -10883,4 +10883,13 @@
 	  SaeHie Park (2015-08-25).
 	* drivers/rwbuffer.c: Fix some logic errors.  From Dmitry Nikolaev
 	  via Juha Niskanen (2015-08-26).
+	* net/socket and net/tcp: Fix a problem in whent there are multiple
+	  network devices.  Polls were being sent to all TCP sockets before.
+	  This is not good because it means that packets may sometimes be
+	  sent out on the wrong device.  That is inefficient because it
+	  will cause retransmissions and bad performance.  But, worse, when
+	  one of the devices is not Ethernet, it will have a different MSS
+	  and, as a result, incorrect data transfers can cause crashes.
+	  The fix is to lock into a single device once the MSS is locked
+	  locked down (2015-08-27).
 
diff --git a/net/socket/connect.c b/net/socket/connect.c
index 77443a775e..00e2db1e05 100644
--- a/net/socket/connect.c
+++ b/net/socket/connect.c
@@ -278,22 +278,32 @@ static uint16_t psock_connect_interrupt(FAR struct net_driver_s *dev,
 
 #ifdef CONFIG_NET_IPv4
 #ifdef CONFIG_NET_IPv6
-  if (pstate->tc_conn->domain == PF_INET)
+      if (pstate->tc_conn->domain == PF_INET)
 #endif
-    {
-      pstate->tc_conn->mss = TCP_IPv4_INITIAL_MSS(dev);
-    }
+        {
+          pstate->tc_conn->mss = TCP_IPv4_INITIAL_MSS(dev);
+        }
 #endif /* CONFIG_NET_IPv4 */
 
 #ifdef CONFIG_NET_IPv6
 #ifdef CONFIG_NET_IPv4
-  else
+      else
 #endif
-    {
-      pstate->tc_conn->mss = TCP_IPv4_INITIAL_MSS(dev);
-    }
+        {
+          pstate->tc_conn->mss = TCP_IPv4_INITIAL_MSS(dev);
+        }
 #endif /* CONFIG_NET_IPv6 */
 
+#ifdef CONFIG_NETDEV_MULTINIC
+      /* We now have to filter all outgoing transfers so that they use only
+       * the MSS of this device.
+       */
+
+      DEBUGASSERT(pstate->tc_conn->dev == NULL ||
+                  pstate->tc_conn->dev == dev);
+      pstate->tc_conn->dev = dev;
+
+#endif /* CONFIG_NETDEV_MULTINIC */
 #endif /* CONFIG_NET_MULTILINK */
 
       /* Wake up the waiting thread */
diff --git a/net/socket/net_sendfile.c b/net/socket/net_sendfile.c
index 443a66357d..9bb413cefd 100644
--- a/net/socket/net_sendfile.c
+++ b/net/socket/net_sendfile.c
@@ -324,6 +324,18 @@ static uint16_t sendfile_interrupt(FAR struct net_driver_s *dev, FAR void *pvcon
   FAR struct sendfile_s *pstate = (FAR struct sendfile_s *)pvpriv;
   int ret;
 
+#ifdef CONFIG_NETDEV_MULTINIC
+  /* The TCP socket is connected and, hence, should be bound to a device.
+   * Make sure that the polling device is the own that we are bound to.
+   */
+
+  DEBUGASSERT(conn->dev != NULL);
+  if (dev != conn->dev)
+    {
+      return flags;
+    }
+#endif
+
   nllvdbg("flags: %04x acked: %d sent: %d\n",
           flags, pstate->snd_acked, pstate->snd_sent);
 
diff --git a/net/tcp/tcp_conn.c b/net/tcp/tcp_conn.c
index 32ea2d6901..f6e33e6ac0 100644
--- a/net/tcp/tcp_conn.c
+++ b/net/tcp/tcp_conn.c
@@ -1003,6 +1003,13 @@ FAR struct tcp_conn_s *tcp_alloc_accept(FAR struct net_driver_s *dev,
           net_ipv6addr_copy(conn->u.ipv6.raddr, ip->srcipaddr);
 #ifdef CONFIG_NETDEV_MULTINIC
           net_ipv6addr_copy(conn->u.ipv6.laddr, ip->destipaddr);
+
+          /* We now have to filter all outgoing transfers so that they use
+           * only the MSS of this device.
+           */
+
+          DEBUGASSERT(conn->dev == NULL || conn->dev == dev);
+          conn->dev = dev;
 #endif
 
           /* Find the device that can receive packets on the network
@@ -1028,6 +1035,13 @@ FAR struct tcp_conn_s *tcp_alloc_accept(FAR struct net_driver_s *dev,
 #ifdef CONFIG_NETDEV_MULTINIC
           net_ipv4addr_copy(conn->u.ipv4.laddr,
                             net_ip4addr_conv32(ip->destipaddr));
+
+          /* We now have to filter all outgoing transfers so that they use
+           * only the MSS of this device.
+           */
+
+          DEBUGASSERT(conn->dev == NULL || conn->dev == dev);
+          conn->dev = dev;
 #endif
 
           /* Find the device that can receive packets on the network
diff --git a/net/tcp/tcp_send_buffered.c b/net/tcp/tcp_send_buffered.c
index 3044b5f030..34e9100ad0 100644
--- a/net/tcp/tcp_send_buffered.c
+++ b/net/tcp/tcp_send_buffered.c
@@ -338,6 +338,18 @@ static uint16_t psock_send_interrupt(FAR struct net_driver_s *dev,
   FAR struct tcp_conn_s *conn = (FAR struct tcp_conn_s *)pvconn;
   FAR struct socket *psock = (FAR struct socket *)pvpriv;
 
+#ifdef CONFIG_NETDEV_MULTINIC
+  /* The TCP socket is connected and, hence, should be bound to a device.
+   * Make sure that the polling device is the own that we are bound to.
+   */
+
+  DEBUGASSERT(conn->dev != NULL);
+  if (dev != conn->dev)
+    {
+      return flags;
+    }
+#endif
+
   nllvdbg("flags: %04x\n", flags);
 
   /* If this packet contains an acknowledgement, then update the count of
diff --git a/net/tcp/tcp_send_unbuffered.c b/net/tcp/tcp_send_unbuffered.c
index b8052a1ec7..efffe4793f 100644
--- a/net/tcp/tcp_send_unbuffered.c
+++ b/net/tcp/tcp_send_unbuffered.c
@@ -290,6 +290,18 @@ static uint16_t tcpsend_interrupt(FAR struct net_driver_s *dev,
   FAR struct tcp_conn_s *conn = (FAR struct tcp_conn_s *)pvconn;
   FAR struct send_s *pstate = (FAR struct send_s *)pvpriv;
 
+#ifdef CONFIG_NETDEV_MULTINIC
+  /* The TCP socket is connected and, hence, should be bound to a device.
+   * Make sure that the polling device is the own that we are bound to.
+   */
+
+  DEBUGASSERT(conn->dev != NULL);
+  if (dev != conn->dev)
+    {
+      return flags;
+    }
+#endif
+
   nllvdbg("flags: %04x acked: %d sent: %d\n",
           flags, pstate->snd_acked, pstate->snd_sent);