diff --git a/target/linux/ramips/base-files/lib/preinit/07_set_preinit_iface_ramips b/target/linux/ramips/base-files/lib/preinit/07_set_preinit_iface_ramips
index 003a4dda7b..68c1285eb4 100644
--- a/target/linux/ramips/base-files/lib/preinit/07_set_preinit_iface_ramips
+++ b/target/linux/ramips/base-files/lib/preinit/07_set_preinit_iface_ramips
@@ -3,27 +3,54 @@
 # Copyright (C) 2013 OpenWrt.org
 #
 
+. /lib/functions.sh
+
+ramips_switchdev_from_soc() {
+	# The ethernet switch driver enables VLAN by default, but
+	# failsafe uses eth0, making the device unreachable:
+	# https://dev.openwrt.org/ticket/18768
+
+	local switchdev
+	local RT3X5X=$(grep -E "(RT3.5|RT5350|MT7628|MT7688|MT7620|MT7621)" /proc/cpuinfo)
+
+	[ -n "$RT3X5X" ] || return 1
+
+	case "$RT3X5X" in
+	*MT7620*)
+		switchdev=mt7620
+		;;
+	*MT7621*)
+		switchdev=mt7530
+		;;
+	*)
+		switchdev=rt305x
+		;;
+	esac
+
+	echo "$switchdev"
+}
+
+ramips_switchdev_from_board() {
+	# For these devices, external ethernet switch should be used
+	# instead of the SoC internal switch.
+
+	local switchdev
+	local board=$(board_name)
+
+	case "$board" in
+	esac
+
+	echo "$switchdev"
+}
+
 ramips_set_preinit_iface() {
-	RT3X5X=$(grep -E "(RT3.5|RT5350|MT7628|MT7688|MT7620|MT7621)" /proc/cpuinfo)
-
-	if [ -n "${RT3X5X}" ]; then
-		# The ethernet switch driver enables VLAN by default, but
-		# failsafe uses eth0, making the device unreachable:
-		# https://dev.openwrt.org/ticket/18768
-		case "${RT3X5X}" in
-		*MT7620*)
-			ralink_switchdev=mt7620
-			;;
-		*MT7621*)
-			ralink_switchdev=mt7530
-			;;
-		*)
-			ralink_switchdev=rt305x
-			;;
-		esac
-		swconfig dev $ralink_switchdev set reset 1
-		swconfig dev $ralink_switchdev set enable_vlan 0
-		swconfig dev $ralink_switchdev set apply 1
+	local switchdev=$(ramips_switchdev_from_board)
+	[ -n "$switchdev" ] || switchdev=$(ramips_switchdev_from_soc)
+
+	if [ -n "$switchdev" ]; then
+		swconfig dev $switchdev set reset 1
+		swconfig dev $switchdev set enable_vlan 0
+		swconfig dev $switchdev set apply 1
 	fi
 
 	ifname=eth0