diff --git a/assets/js/components/Config/DeviceModal/DeviceModalBase.vue b/assets/js/components/Config/DeviceModal/DeviceModalBase.vue
index f77385766..27200f665 100644
--- a/assets/js/components/Config/DeviceModal/DeviceModalBase.vue
+++ b/assets/js/components/Config/DeviceModal/DeviceModalBase.vue
@@ -352,6 +352,7 @@ export default defineComponent({
 		},
 		apiData(): ApiData {
 			let data: ApiData = {
+				...this.modbusDefaults,
 				...this.values,
 			};
 			if (this.values.type === ConfigType.Template && this.templateName) {
diff --git a/tests/config-param-service-modbus.spec.ts b/tests/config-param-service-modbus.spec.ts
index 6216f84e1..006b425d9 100644
--- a/tests/config-param-service-modbus.spec.ts
+++ b/tests/config-param-service-modbus.spec.ts
@@ -64,4 +64,23 @@ test.describe("modbus service expansion", async () => {
     await meterModal.getByLabel("IP address or hostname").fill("192.168.1.1");
     await expect(meterModal.getByLabel("Test value")).toHaveValue("100,id:2,tcp");
   });
+
+  test("template defaults are included in validation request", async ({ page }) => {
+    const meterModal = await openMeterModal(page);
+
+    // Fill required fields
+    await meterModal.getByLabel("Register address").fill("100");
+    await meterModal.getByLabel("IP address or hostname").fill("192.168.1.1");
+    await meterModal.getByLabel("Test value").fill("test");
+
+    // Intercept validation POST request
+    const requestPromise = page.waitForRequest(
+      (req) => req.url().includes("/api/config/test/meter") && req.method() === "POST"
+    );
+    await meterModal.getByRole("button", { name: "Save" }).click();
+    const body = (await requestPromise).postDataJSON();
+
+    // Template has id: 2 - verify it's included even though user didn't set it
+    expect(body.id).toBe(2);
+  });
 });