diff --git a/src/etc/inc/interfaces.inc b/src/etc/inc/interfaces.inc
index 7a21be6ab..85e015bc8 100644
--- a/src/etc/inc/interfaces.inc
+++ b/src/etc/inc/interfaces.inc
@@ -4001,7 +4001,7 @@ function get_interface_ip($interface = 'wan')
         }
     }
 
-    $curip = find_interface_ip($realif);
+    $curip = find_interface_ip($realif, true);
     if (is_ipaddrv4($curip)) {
         return $curip;
     }
@@ -4023,7 +4023,7 @@ function get_interface_ipv6($interface = 'wan')
     }
 
     $curip = isset($config['interfaces'][$interface]['dhcp6prefixonly']) ?
-        find_interface_ipv6_ll($realif) : find_interface_ipv6($realif);
+        find_interface_ipv6_ll($realif, true) : find_interface_ipv6($realif, true);
     if (is_ipaddrv6($curip)) {
         return $curip;
     }
@@ -4043,12 +4043,10 @@ function get_interface_subnet($interface = 'wan')
         }
     }
 
-    if (does_interface_exist($realif)) {
-        $ifinfo = legacy_get_interface_addresses($realif);
-        if (isset($ifinfo['subnetbits'])) {
-            /* return first subnet size found */
-            return $ifinfo['subnetbits'];
-        }
+    $ifinfo = legacy_get_interface_addresses($realif);
+    if (isset($ifinfo['subnetbits'])) {
+        /* return first subnet size found */
+        return $ifinfo['subnetbits'];
     }
 
     return null;
@@ -4060,18 +4058,16 @@ function get_interface_subnetv6($interface = 'wan')
     if (!$realif) {
         if (strstr($interface, '_vip')) {
             list($interface, $vhid) = explode('_vip', $interface);
-            $realif = get_real_interface($interface);
+            $realif = get_real_interface($interface, 'inet6');
         } else {
             return null;
         }
     }
 
-    if (does_interface_exist($realif)) {
-        $ifinfo = legacy_get_interface_addresses($realif);
-        if (isset($ifinfo['subnetbits6'])) {
-            /* return first subnet size found */
-            return $ifinfo['subnetbits6'];
-        }
+    $ifinfo = legacy_get_interface_addresses($realif);
+    if (isset($ifinfo['subnetbits6'])) {
+        /* return first subnet size found */
+        return $ifinfo['subnetbits6'];
     }
 
     return null;
diff --git a/src/etc/inc/interfaces.lib.inc b/src/etc/inc/interfaces.lib.inc
index 64dc95f25..bb8c098e7 100644
--- a/src/etc/inc/interfaces.lib.inc
+++ b/src/etc/inc/interfaces.lib.inc
@@ -216,7 +216,10 @@ function legacy_interfaces_details($intf = null)
     $cmd = '/sbin/ifconfig -m ' . $tmp_intf;
     exec($cmd . ' 2>&1', $ifconfig_data, $ret);
     if ($ret) {
-        log_error('The command `' . $cmd . '\' failed to execute ' . implode(' ', $ifconfig_data));
+        /* only error if no explicit interface was choosen */
+        if (empty($intf)) {
+            log_error('The command `' . $cmd . '\' failed to execute ' . implode(' ', $ifconfig_data));
+        }
         return $result;
     }
 
@@ -326,7 +329,14 @@ function legacy_interfaces_details($intf = null)
  */
 function legacy_interface_details($intf)
 {
-    return legacy_interfaces_details($intf)[$intf];
+    $result = array();
+
+    $details = legacy_interfaces_details($intf);
+    if (isset($details[$intf])) {
+        $result = $details[$intf];
+    }
+
+    return $result;
 }
 
 /**