diff --git a/src/etc/inc/filter.lib.inc b/src/etc/inc/filter.lib.inc
index d868628ec..ca8e6bb96 100644
--- a/src/etc/inc/filter.lib.inc
+++ b/src/etc/inc/filter.lib.inc
@@ -376,29 +376,33 @@ function filter_core_rules_system($fw, $defaults)
         );
     }
 
-    // out from this Firewall, using the selected gateway.
-    foreach ($fw->getInterfaceMapping() as $ifdescr => $ifcfg) {
-        if (!isset($ifcfg['virtual']) && $ifcfg['if'] != 'lo0') {
-            $intf_has_v4 = false;
-            $intf_has_v6 = false;
-            foreach (legacy_getall_interface_addresses($ifcfg['if']) as $addr) {
-                $intf_has_v4 = $intf_has_v4 || is_subnetv4($addr);
-                $intf_has_v6 = $intf_has_v6 || is_subnetv6($addr);
-            }
-            foreach ($fw->getInterfaceGateways($ifcfg['if']) as $gwname) {
-                $gwproto = $fw->getGateway($gwname)['proto'];
-                // only try to add gateway rules for traffic leaving this interface when the correct protocol is
-                // assigned to the interface (e.g. no ipv4 gateway when :network doesn't resolve to an ipv4 network)
-                if (($gwproto == 'inet' && $intf_has_v4) || ($gwproto == 'inet6' && $intf_has_v6)) {
-                    $fw->registerFilterRule(100000,
-                      array('from' => $ifcfg['if'], 'direction' => 'out', 'gateway' => $gwname,
-                        'destination' => array('network'=> $ifdescr, "not" => true),
-                        'statetype' => 'keep',
-                        'allowopts' => true,
-                        'quick' => false,
-                        'label' => "let out anything from firewall host itself"),
-                      $defaults['pass']
-                    );
+    // [out from this Firewall, using the selected gateway].
+    // Our default setting has been to force traffic leaving a specific interface to use the associated gateway.
+    // This behaviour can be disabled, so settings can be customized using manual firewall rules.
+    if (empty($config['system']['pf_disable_force_gw'])) {
+        foreach ($fw->getInterfaceMapping() as $ifdescr => $ifcfg) {
+            if (!isset($ifcfg['virtual']) && $ifcfg['if'] != 'lo0') {
+                $intf_has_v4 = false;
+                $intf_has_v6 = false;
+                foreach (legacy_getall_interface_addresses($ifcfg['if']) as $addr) {
+                    $intf_has_v4 = $intf_has_v4 || is_subnetv4($addr);
+                    $intf_has_v6 = $intf_has_v6 || is_subnetv6($addr);
+                }
+                foreach ($fw->getInterfaceGateways($ifcfg['if']) as $gwname) {
+                    $gwproto = $fw->getGateway($gwname)['proto'];
+                    // only try to add gateway rules for traffic leaving this interface when the correct protocol is
+                    // assigned to the interface (e.g. no ipv4 gateway when :network doesn't resolve to an ipv4 network)
+                    if (($gwproto == 'inet' && $intf_has_v4) || ($gwproto == 'inet6' && $intf_has_v6)) {
+                        $fw->registerFilterRule(100000,
+                          array('from' => $ifcfg['if'], 'direction' => 'out', 'gateway' => $gwname,
+                            'destination' => array('network'=> $ifdescr, "not" => true),
+                            'statetype' => 'keep',
+                            'allowopts' => true,
+                            'quick' => false,
+                            'label' => "let out anything from firewall host itself"),
+                          $defaults['pass']
+                        );
+                    }
                 }
             }
         }
diff --git a/src/www/system_advanced_firewall.php b/src/www/system_advanced_firewall.php
index 271667694..a272a549f 100644
--- a/src/www/system_advanced_firewall.php
+++ b/src/www/system_advanced_firewall.php
@@ -60,6 +60,7 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
     $pconfig['gw_switch_default'] = isset($config['system']['gw_switch_default']);
     $pconfig['lb_use_sticky'] = isset($config['system']['lb_use_sticky']);
     $pconfig['pf_share_forward'] = isset($config['system']['pf_share_forward']);
+    $pconfig['pf_disable_force_gw'] = isset($config['system']['pf_disable_force_gw']);
     $pconfig['srctrack'] = !empty($config['system']['srctrack']) ? $config['system']['srctrack'] : null;
     if (!isset($config['system']['disablenatreflection'])) {
         $pconfig['natreflection'] = "purenat";
@@ -103,6 +104,12 @@ if ($_SERVER['REQUEST_METHOD'] === 'GET') {
             unset($config['system']['pf_share_forward']);
         }
 
+        if (!empty($pconfig['pf_disable_force_gw'])) {
+            $config['system']['pf_disable_force_gw'] = true;
+        } elseif (isset($config['system']['pf_disable_force_gw'])) {
+            unset($config['system']['pf_disable_force_gw']);
+        }
+
         if (!empty($pconfig['lb_use_sticky'])) {
             $config['system']['lb_use_sticky'] = true;
         } elseif (isset($config['system']['lb_use_sticky'])) {
@@ -410,6 +417,18 @@ include("head.inc");
                     </div>
                   </td>
                 </tr>
+                <tr>
+                  <td><a id="help_pf_disable_force_gw" href="#" class="showhelp"><i class="fa fa-info-circle"></i></a> <?=gettext('Disable force gateway');?> </td>
+                  <td>
+                    <input name="pf_disable_force_gw" type="checkbox" id="pf_disable_force_gw" value="yes" <?= !empty($pconfig['pf_disable_force_gw']) ? 'checked="checked"' : '' ?>/>
+                    <strong><?=gettext('Disable automatic rules which force local services to use the assigned interface gateway.'); ?></strong><br />
+                    <div class="hidden" for="help_pf_disable_force_gw">
+                      <?= gettext('Outgoing packets from this firewall on an interface which has a gateway ' .
+                                  'will normally use the specified gateway for that interface. ' .
+                                  'When this option is set, the default routing rules apply (automatic rules will be disabled).') ?>
+                    </div>
+                  </td>
+                </tr>
                 <tr>
                   <th colspan="2" valign="top" class="listtopic"><?=gettext("Schedules"); ?></th>
                 </tr>