diff --git a/target/linux/lantiq/dts/DGN3500.dtsi b/target/linux/lantiq/dts/DGN3500.dtsi
index 569fa9f11c..bc50e4ae65 100644
--- a/target/linux/lantiq/dts/DGN3500.dtsi
+++ b/target/linux/lantiq/dts/DGN3500.dtsi
@@ -168,7 +168,7 @@
 		#size-cells = <1>;
 		compatible = "jedec,spi-nor";
 		reg = <4 0>;
-		spi-max-frequency = <30000000>;
+		spi-max-frequency = <20000000>;
 
 		partitions {
 			compatible = "fixed-partitions";