Index: sys/netinet/tcp_input.c
===================================================================
--- sys/netinet/tcp_input.c
+++ sys/netinet/tcp_input.c
@@ -3191,15 +3191,9 @@
 			 * when trimming from the head.
 			 */
 			tcp_seq temp = save_start;
-			if (tlen || (th->th_seq != tp->rcv_nxt)) {
-				/*
-				 * We add the th_seq != rcv_nxt to
-				 * catch the case of a stand alone out
-				 * of order FIN.
-				 */
-				thflags = tcp_reass(tp, th, &temp, &tlen, m);
-				tp->t_flags |= TF_ACKNOW;
-			}
+
+			thflags = tcp_reass(tp, th, &temp, &tlen, m);
+			tp->t_flags |= TF_ACKNOW;
 		}
 		if ((tp->t_flags & TF_SACK_PERMIT) &&
 		    (save_tlen > 0) &&
Index: sys/netinet/tcp_reass.c
===================================================================
--- sys/netinet/tcp_reass.c
+++ sys/netinet/tcp_reass.c
@@ -571,6 +571,7 @@
 		 * the rcv_nxt <-> rcv_wnd but thats
 		 * already done for us by the caller.
 		 */
+strip_fin:
 #ifdef TCP_REASS_COUNTERS
 		counter_u64_add(tcp_zero_input, 1);
 #endif
@@ -579,6 +580,19 @@
 		tcp_reass_log_dump(tp);
 #endif
 		return (0);
+	} else if ((*tlenp == 0) &&
+		   (th->th_flags & TH_FIN) &&
+		   !TCPS_HAVEESTABLISHED(tp->t_state)) {
+		/*
+		 * We have not established, and we
+		 * have a FIN and no data. Lets treat
+		 * this as the same as if the FIN were
+		 * not present. We don't want to save
+		 * the FIN bit in a reassembly buffer
+		 * we want to get established first before
+		 * we do that (the peer will retransmit).
+		 */
+		goto strip_fin;
 	}
 	/*
 	 * Will it fit?
Index: sys/netinet/tcp_stacks/bbr.c
===================================================================
--- sys/netinet/tcp_stacks/bbr.c
+++ sys/netinet/tcp_stacks/bbr.c
@@ -8320,15 +8320,9 @@
 			 * trimming from the head.
 			 */
 			tcp_seq temp = save_start;
-			if (tlen || (th->th_seq != tp->rcv_nxt)) {
-				/*
-				 * We add the th_seq != rcv_nxt to
-				 * catch the case of a stand alone out
-				 * of order FIN.
-				 */
-				thflags = tcp_reass(tp, th, &temp, &tlen, m);
-				tp->t_flags |= TF_ACKNOW;
-			}
+
+			thflags = tcp_reass(tp, th, &temp, &tlen, m);
+			tp->t_flags |= TF_ACKNOW;
 		}
 		if ((tp->t_flags & TF_SACK_PERMIT) &&
 		    (save_tlen > 0) &&
Index: sys/netinet/tcp_stacks/rack.c
===================================================================
--- sys/netinet/tcp_stacks/rack.c
+++ sys/netinet/tcp_stacks/rack.c
@@ -10235,15 +10235,10 @@
 			 * trimming from the head.
 			 */
 			tcp_seq temp = save_start;
-			if (tlen || (th->th_seq != tp->rcv_nxt)) {
-				/*
-				 * We add the th_seq != rcv_nxt to
-				 * catch the case of a stand alone out
-				 * of order FIN.
-				 */
-				thflags = tcp_reass(tp, th, &temp, &tlen, m);
-				tp->t_flags |= TF_ACKNOW;
-			}
+
+			thflags = tcp_reass(tp, th, &temp, &tlen, m);
+			tp->t_flags |= TF_ACKNOW;
+
 		}
 		if ((tp->t_flags & TF_SACK_PERMIT) &&
 		    (save_tlen > 0) &&
Index: sys/netinet/tcp_usrreq.c
===================================================================
--- sys/netinet/tcp_usrreq.c
+++ sys/netinet/tcp_usrreq.c
@@ -2647,22 +2647,6 @@
 		tcp_state_change(tp, TCPS_LAST_ACK);
 		break;
 	}
-	if ((tp->t_state == TCPS_LAST_ACK) &&
-	    (tp->t_flags & TF_SENTFIN)) {
-		/*
-		 * If we have reached LAST_ACK, and
-		 * we sent a FIN (e.g. via MSG_EOR), then
-		 * we really should move to either FIN_WAIT_1
-		 * or FIN_WAIT_2 depending on snd_max/snd_una.
-		 */
-		if (tp->snd_una == tp->snd_max) {
-			/* The FIN is acked */
-			tcp_state_change(tp, TCPS_FIN_WAIT_2);
-		} else {
-			/* The FIN is still outstanding */
-			tcp_state_change(tp, TCPS_FIN_WAIT_1);
-		}
-	}
 	if (tp->t_state >= TCPS_FIN_WAIT_2) {
 		soisdisconnected(tp->t_inpcb->inp_socket);
 		/* Prevent the connection hanging in FIN_WAIT_2 forever. */