diff --git a/target/linux/ramips/mt7621/base-files/lib/preinit/07_mt7621_bringup_dsa_master b/target/linux/ramips/mt7621/base-files/lib/preinit/07_mt7621_bringup_dsa_master
new file mode 100644
index 00000000000..7a112521685
--- /dev/null
+++ b/target/linux/ramips/mt7621/base-files/lib/preinit/07_mt7621_bringup_dsa_master
@@ -0,0 +1,22 @@
+#!/bin/sh
+
+. /lib/functions.sh
+
+mt7621_bringup_dsa_master() {
+    local board=$(board_name)
+    local masterif
+
+    case "$board" in
+    ubiquiti,edgerouterx|\
+	ubiquiti,edgerouterx-sfp)
+        masterif="dsa"
+        ;;
+    *)
+        masterif="eth0"
+        ;;
+    esac
+
+    ifconfig $masterif up
+}
+
+boot_hook_add preinit_main mt7621_bringup_dsa_master
\ No newline at end of file