--- filter.inc.bak	2018-06-06 11:38:15.442508000 +1000
+++ filter.inc	2018-06-07 10:58:42.179627000 +1000
@@ -218,14 +218,74 @@
 			}
 			$gwstatus =& $a_gateways[$gateway['monitor']];
 			if (strstr($gwstatus['status'], "down")) {
-				$any_gateway_down = true;
-				break;
+				if (!empty($gateway['interface']))
+					$gwiface = $gateway['interface'];
+				else
+					$gwiface = get_real_interface($gateway['friendlyiface']);
+
+			        log_error("Removing states for interface {$gwiface}");
+			        $nat_states = exec_command("/sbin/pfctl -i {$gwiface} -ss");
+
+ 			        $cleared_states = array();
+			        foreach (explode("\n", $nat_states) as $nat_state) {
+
+					$ipv4_num_matches = preg_match_all('/([\d\.]+):[\d]+[\s-><)]+/i', $nat_state, $ipv4_matches, PREG_SET_ORDER);
+
+					if ($ipv4_num_matches == 3) {
+
+						$natsrc = $ipv4_matches[1][1];
+						$dst = $ipv4_matches[2][1];
+
+						if (!(empty($natsrc) || empty($dst) || in_array("{$natsrc},{$dst}", $cleared_states))) {
+
+							$cleared_states[] = "{$natsrc},{$dst}";
+							pfSense_kill_states($natsrc, $dst);
+
+						}
+
+						$src = $ipv4_matches[0][1];
+						$dst = $ipv4_matches[2][1];
+
+						if (!(empty($src) || empty($dst) || in_array("{$src},{$dst}", $cleared_states))) {
+
+							$cleared_states[] = "{$src},{$dst}";
+							pfSense_kill_states($src, $dst);
+
+						}
+
+					} elseif ($ipv4_num_matches == 2) {
+
+						$src = $ipv4_matches[0][1];
+						$dst = $ipv4_matches[1][1];
+
+						if (!(empty($src) || empty($dst) || in_array("{$src},{$dst}", $cleared_states))) {
+
+							$cleared_states[] = "{$src},{$dst}";
+							pfSense_kill_states($src, $dst);
+
+						}
+					}
+
+					$ipv6_num_matches = preg_match_all('/([\da-f:]+)\[[\d]+\]+[\s-><]+/i', $nat_state, $ipv6_matches, PREG_SET_ORDER);
+
+					if ($ipv6_num_matches == 2) {
+
+						$src = $ipv6_matches[0][1];
+						$dst = $ipv6_matches[1][1];
+
+						if (!(empty($src) || empty($dst) || in_array("{$src},{$dst}", $cleared_states))) {
+
+							$cleared_states[] = "{$src},{$dst}";
+							pfSense_kill_states($src, $dst);
+
+						}
+
+					}
+			        }
+			        mwexec("/sbin/pfctl -i {$gwiface} -Fs", true);
 			}
 		}
 	}
-	if ($any_gateway_down == true) {
-		mwexec("/sbin/pfctl -Fs");
-	}
 }
 
 /* reload filter sync */