--- sys/netproto/802_11/wlan/ieee80211_tdma.c	2026-06-29 12:51:19.000000000 +0000
+++ /tmp/opencode/fixsrc/sys/netproto/802_11/wlan/ieee80211_tdma.c	2026-10-24 13:14:50.721342845 +0000
@@ -285,6 +285,10 @@
 		    2 * vap->iv_bmissthreshold * ts->tdma_bintval *
 		    ((ts->tdma_slotcnt * ts->tdma_slotlen) / 1024));
 		vap->iv_swbmiss_count = 0;
+		/* DF-2579 fix: the uint16_t store of TU_TO_TICKS() may
+		 * truncate to 0 (callout storm); floor at one tick. */
+		if (vap->iv_swbmiss_period == 0)
+			vap->iv_swbmiss_period = 1;
 		callout_reset(&vap->iv_swbmiss, vap->iv_swbmiss_period,
 			ieee80211_swbmiss, vap);
 	}