diff --git a/port/netxduo-amiga/inc/nx_user.h b/port/netxduo-amiga/inc/nx_user.h
index f8796a6ab..add106273 100644
--- a/port/netxduo-amiga/inc/nx_user.h
+++ b/port/netxduo-amiga/inc/nx_user.h
@@ -118,9 +118,15 @@ extern struct TX_THREAD_STRUCT *_nx_ip_input_thread;
    BSD_TCP_WINDOW_MAX at 262,144 the buffer's half would be 128 KB, one
    acknowledgment per ninety segments, and every one of them releases a
    burst that size at the sender's line rate into the card's receive ring.
-   Pinned at what the largest pre-scaling buffer produced, so a machine that
-   was already at the old ceiling acknowledges exactly as it did. */
-#define NX_TCP_ACK_THRESHOLD_MAX                50176
+   At 50,176 an acknowledgment carried 35-48 segments, fewer than two per
+   sender burst.  Leading model for the #89 stalls (hw4, not yet shown to go
+   away): two lost acknowledgments leave the sender nothing until a probe and
+   the 100-200 ms delayed-ACK hold.  At eight segments the crossing falls
+   inside the first GRO run (sana2_rx.c, 16 frames), so one acknowledgment
+   leaves per run.  A1200 WiFiPi, main 95e3983a, 5 control legs vs ONE test
+   leg: 60,932 -> 23,360 bytes per acknowledgment (median), 89 -> 218 per
+   second, 41.8-44.0 -> 50.3 Mbit/s inbound. */
+#define NX_TCP_ACK_THRESHOLD_MAX                11680
 
 /* The clock the SYN cache times a handshake with (nx_tcp_syncache.c): the
    E-Clock in milliseconds, src/common/compat.c.  An accepted socket then