diff --git a/arch/arm/src/common/ameba/ameba_wlan.c b/arch/arm/src/common/ameba/ameba_wlan.c
index 48f15d6ecef..fa6622cfa00 100644
--- a/arch/arm/src/common/ameba/ameba_wlan.c
+++ b/arch/arm/src/common/ameba/ameba_wlan.c
@@ -226,8 +226,13 @@ static int ameba_wlan_transmit(struct netdev_lowerhalf_s *dev,
 
   if (ret != 0)
     {
-      /* NP skb pool full: let the upper half recycle the packet and pause
-       * the poll (backpressure).  Do NOT free here.
+      /* NP host skb pool full: recycle the packet (do NOT free) and
+       * let the upper half pause the poll -- genuine backpressure.
+       * This stays off the hot path because CONFIG_NET_SEND_BUFSIZE
+       * bounds a stream's in-flight data and the NP drains at line
+       * rate, so the transient host skb backlog stays well under the
+       * pool (skb_num_ap).  A momentary full pool just pauses here and
+       * resumes on the next poll.
        */
 
       return -EIO;
diff --git a/arch/arm/src/common/ameba/wifi/ameba_wifi.c b/arch/arm/src/common/ameba/wifi/ameba_wifi.c
index 0a9eba93013..75f23cd4ec5 100644
--- a/arch/arm/src/common/ameba/wifi/ameba_wifi.c
+++ b/arch/arm/src/common/ameba/wifi/ameba_wifi.c
@@ -108,17 +108,19 @@ int ameba_wifi_start(void)
       g_rtw_task_size.ipc_unblk_api_task = 4096;
     }
 
-  /* Host TX skb pool: the SDK default (4) is too small for sustained TCP
-   * TX.  The pool drains, whc_ipc_host_send() returns -2 (drops the frame),
-   * TCP retransmits, and under load the retransmits exhaust and the link is
-   * torn down (send -> ENOTCONN).  UDP tolerates the drops so is unaffected.
-   * A modest pool keeps TCP TX stable; 16 skbs ~= 27 KB of AP heap (vs 53 KB
-   * at 32).
+  /* Host TX skb pool: the SDK default (4) is too small for sustained
+   * TCP TX (the pool drains, whc_ipc_host_send() returns -2, the frame
+   * is dropped and TCP stalls).  CONFIG_NET_SEND_BUFSIZE now bounds a
+   * stream's in-flight data and the NP drains at line rate, so the pool
+   * only has to cover the NP's transient TX backlog, not the whole
+   * window -- 8 skbs (~13 KB of AP heap) is enough here, well above the
+   * SDK stack's own high-throughput profile of 5.  Raise if bulk TX
+   * regresses.
    */
 
-  if (wifi_user_config.skb_num_ap < 16)
+  if (wifi_user_config.skb_num_ap < 8)
     {
-      wifi_user_config.skb_num_ap = 16;
+      wifi_user_config.skb_num_ap = 8;
     }
 
   whc_ipc_host_init();
diff --git a/boards/arm/rtl8720f/rtl8720f_evb/configs/nsh/defconfig b/boards/arm/rtl8720f/rtl8720f_evb/configs/nsh/defconfig
index b18613f488f..f5a19d5f619 100644
--- a/boards/arm/rtl8720f/rtl8720f_evb/configs/nsh/defconfig
+++ b/boards/arm/rtl8720f/rtl8720f_evb/configs/nsh/defconfig
@@ -28,7 +28,7 @@ CONFIG_FS_PROCFS=y
 CONFIG_FS_TMPFS=y
 CONFIG_IDLETHREAD_STACKSIZE=4096
 CONFIG_INIT_ENTRYPOINT="nsh_main"
-CONFIG_IOB_BUFSIZE=400
+CONFIG_IOB_BUFSIZE=512
 CONFIG_IOB_NBUFFERS=100
 CONFIG_IOB_NCHAINS=36
 CONFIG_IOB_THROTTLE=40
@@ -50,11 +50,14 @@ CONFIG_NET_ARP_IPIN=y
 CONFIG_NET_BROADCAST=y
 CONFIG_NET_ETH_PKTSIZE=1514
 CONFIG_NET_ICMP_SOCKET=y
+CONFIG_NET_RECV_BUFSIZE=10000
+CONFIG_NET_SEND_BUFSIZE=16384
 CONFIG_NET_TCP=y
 CONFIG_NET_TCP_DELAYED_ACK=y
 CONFIG_NET_TCP_KEEPALIVE=y
 CONFIG_NET_TCP_NOTIFIER=y
-CONFIG_NET_TCP_SELECTIVE_ACK=y
+CONFIG_NET_TCP_OUT_OF_ORDER=y
+CONFIG_NET_TCP_OUT_OF_ORDER_BUFSIZE=10000
 CONFIG_NET_TCP_WRITE_BUFFERS=y
 CONFIG_NET_UDP=y
 CONFIG_NSH_BUILTIN_APPS=y
diff --git a/boards/arm/rtl8721dx/pke8721daf/configs/nsh/defconfig b/boards/arm/rtl8721dx/pke8721daf/configs/nsh/defconfig
index e50b5c94877..7ff53c25adb 100644
--- a/boards/arm/rtl8721dx/pke8721daf/configs/nsh/defconfig
+++ b/boards/arm/rtl8721dx/pke8721daf/configs/nsh/defconfig
@@ -28,7 +28,7 @@ CONFIG_FS_PROCFS=y
 CONFIG_FS_TMPFS=y
 CONFIG_IDLETHREAD_STACKSIZE=4096
 CONFIG_INIT_ENTRYPOINT="nsh_main"
-CONFIG_IOB_BUFSIZE=400
+CONFIG_IOB_BUFSIZE=512
 CONFIG_IOB_NBUFFERS=100
 CONFIG_IOB_NCHAINS=36
 CONFIG_IOB_THROTTLE=40
@@ -50,11 +50,14 @@ CONFIG_NET_ARP_IPIN=y
 CONFIG_NET_BROADCAST=y
 CONFIG_NET_ETH_PKTSIZE=1514
 CONFIG_NET_ICMP_SOCKET=y
+CONFIG_NET_RECV_BUFSIZE=10000
+CONFIG_NET_SEND_BUFSIZE=16384
 CONFIG_NET_TCP=y
 CONFIG_NET_TCP_DELAYED_ACK=y
 CONFIG_NET_TCP_KEEPALIVE=y
 CONFIG_NET_TCP_NOTIFIER=y
-CONFIG_NET_TCP_SELECTIVE_ACK=y
+CONFIG_NET_TCP_OUT_OF_ORDER=y
+CONFIG_NET_TCP_OUT_OF_ORDER_BUFSIZE=10000
 CONFIG_NET_TCP_WRITE_BUFFERS=y
 CONFIG_NET_UDP=y
 CONFIG_NSH_BUILTIN_APPS=y