diff --git a/samples/drivers/mbox/remote/boards/nrf54h20dk_nrf54h20_cpuapp.overlay b/samples/drivers/mbox/remote/boards/nrf54h20dk_nrf54h20_cpuapp.overlay
index 899a7cb40a7..a3ee9c3e060 100644
--- a/samples/drivers/mbox/remote/boards/nrf54h20dk_nrf54h20_cpuapp.overlay
+++ b/samples/drivers/mbox/remote/boards/nrf54h20dk_nrf54h20_cpuapp.overlay
@@ -18,3 +18,7 @@
 &cpurad_bellboard {
 	status = "okay";
 };
+
+&uart136 {
+	/delete-property/ hw-flow-control;
+};
diff --git a/samples/drivers/mbox/remote/boards/nrf54h20dk_nrf54h20_cpuppr.overlay b/samples/drivers/mbox/remote/boards/nrf54h20dk_nrf54h20_cpuppr.overlay
index 049f2432695..2ad53d26177 100644
--- a/samples/drivers/mbox/remote/boards/nrf54h20dk_nrf54h20_cpuppr.overlay
+++ b/samples/drivers/mbox/remote/boards/nrf54h20dk_nrf54h20_cpuppr.overlay
@@ -18,3 +18,7 @@
 &cpuppr_vevif {
 	status = "okay";
 };
+
+&uart135 {
+	/delete-property/ hw-flow-control;
+};
diff --git a/samples/drivers/mbox/remote/boards/nrf54l15pdk_nrf54l15_cpuflpr.overlay b/samples/drivers/mbox/remote/boards/nrf54l15pdk_nrf54l15_cpuflpr.overlay
index cf232439953..20ce53cf824 100644
--- a/samples/drivers/mbox/remote/boards/nrf54l15pdk_nrf54l15_cpuflpr.overlay
+++ b/samples/drivers/mbox/remote/boards/nrf54l15pdk_nrf54l15_cpuflpr.overlay
@@ -18,3 +18,7 @@
 &cpuflpr_vevif_tx {
 	status = "okay";
 };
+
+&uart30 {
+	/delete-property/ hw-flow-control;
+};
diff --git a/samples/drivers/mbox/remote/boards/nrf54l15pdk_nrf54l15_cpuflpr_xip.overlay b/samples/drivers/mbox/remote/boards/nrf54l15pdk_nrf54l15_cpuflpr_xip.overlay
index cf232439953..20ce53cf824 100644
--- a/samples/drivers/mbox/remote/boards/nrf54l15pdk_nrf54l15_cpuflpr_xip.overlay
+++ b/samples/drivers/mbox/remote/boards/nrf54l15pdk_nrf54l15_cpuflpr_xip.overlay
@@ -18,3 +18,7 @@
 &cpuflpr_vevif_tx {
 	status = "okay";
 };
+
+&uart30 {
+	/delete-property/ hw-flow-control;
+};