diff --git a/app/(app)/device/[friendly_id]/client-page.tsx b/app/(app)/device/[friendly_id]/client-page.tsx
index 6b464b70..4c1dfc22 100644
--- a/app/(app)/device/[friendly_id]/client-page.tsx
+++ b/app/(app)/device/[friendly_id]/client-page.tsx
@@ -125,7 +125,11 @@ export default function DeviceClientPage({
 				...editedDevice,
 				[parent]: {
 					...(editedDevice[parent as keyof Device] as Record<string, unknown>),
-					[child]: value,
+					// Inputs always give strings; the schedule stores seconds as a number
+					[child]:
+						name === "refresh_schedule.default_refresh_rate"
+							? Number.parseInt(value, 10)
+							: value,
 				},
 			});
 		} else {
diff --git a/lib/device/defaults.test.ts b/lib/device/defaults.test.ts
new file mode 100644
index 00000000..cb272abe
--- /dev/null
+++ b/lib/device/defaults.test.ts
@@ -0,0 +1,69 @@
+/// <reference types="jest" />
+import { normalizeRefreshSchedule } from "@/lib/device/defaults";
+
+describe("normalizeRefreshSchedule", () => {
+	it("keeps numeric schedules as they are", () => {
+		expect(
+			normalizeRefreshSchedule({
+				default_refresh_rate: 600,
+				time_ranges: [
+					{ start_time: "23:30", end_time: "06:30", refresh_rate: 6000 },
+				],
+			}),
+		).toEqual({
+			default_refresh_rate: 600,
+			time_ranges: [
+				{ start_time: "23:30", end_time: "06:30", refresh_rate: 6000 },
+			],
+		});
+	});
+
+	it("accepts refresh rates saved as numeric strings", () => {
+		expect(
+			normalizeRefreshSchedule({
+				default_refresh_rate: "600",
+				time_ranges: [
+					{ start_time: "23:30", end_time: "06:30", refresh_rate: "6000" },
+				],
+			}),
+		).toEqual({
+			default_refresh_rate: 600,
+			time_ranges: [
+				{ start_time: "23:30", end_time: "06:30", refresh_rate: 6000 },
+			],
+		});
+	});
+
+	it("parses a JSON string column", () => {
+		expect(normalizeRefreshSchedule('{"default_refresh_rate":"600"}')).toEqual({
+			default_refresh_rate: 600,
+			time_ranges: [],
+		});
+	});
+
+	it("rejects a non-numeric default refresh rate", () => {
+		expect(normalizeRefreshSchedule({ default_refresh_rate: "" })).toBeNull();
+		expect(
+			normalizeRefreshSchedule({ default_refresh_rate: "abc" }),
+		).toBeNull();
+		expect(normalizeRefreshSchedule({ default_refresh_rate: null })).toBeNull();
+	});
+
+	it("drops invalid time ranges but keeps the rest of the schedule", () => {
+		expect(
+			normalizeRefreshSchedule({
+				default_refresh_rate: 600,
+				time_ranges: [
+					{ start_time: "23:30", end_time: "06:30", refresh_rate: "abc" },
+					{ start_time: "12:00", end_time: "13:00", refresh_rate: 60 },
+					null,
+				],
+			}),
+		).toEqual({
+			default_refresh_rate: 600,
+			time_ranges: [
+				{ start_time: "12:00", end_time: "13:00", refresh_rate: 60 },
+			],
+		});
+	});
+});
diff --git a/lib/device/defaults.ts b/lib/device/defaults.ts
index 64aee308..483e0984 100644
--- a/lib/device/defaults.ts
+++ b/lib/device/defaults.ts
@@ -28,6 +28,16 @@ export function serializeRefreshSchedule(schedule: RefreshSchedule): string {
 	return JSON.stringify(schedule);
 }
 
+// Older versions of the device form saved refresh rates as strings ("600"),
+// so accept numeric strings as well as numbers.
+function parseRefreshSeconds(value: unknown): number | null {
+	if (typeof value === "number") return Number.isFinite(value) ? value : null;
+	if (typeof value === "string" && /^\s*\d+\s*$/.test(value)) {
+		return Number.parseInt(value, 10);
+	}
+	return null;
+}
+
 export function normalizeRefreshSchedule(
 	value: unknown,
 ): RefreshSchedule | null {
@@ -40,20 +50,32 @@ export function normalizeRefreshSchedule(
 		}
 	}
 	if (typeof value !== "object" || Array.isArray(value)) return null;
-	const candidate = value as Partial<RefreshSchedule>;
-	if (typeof candidate.default_refresh_rate !== "number") return null;
-	const timeRanges = Array.isArray(candidate.time_ranges)
-		? candidate.time_ranges.filter(
-				(range): range is RefreshSchedule["time_ranges"][number] =>
-					typeof range === "object" &&
-					range !== null &&
-					typeof range.start_time === "string" &&
-					typeof range.end_time === "string" &&
-					typeof range.refresh_rate === "number",
-			)
-		: [];
+	const candidate = value as Record<string, unknown>;
+	const defaultRefreshRate = parseRefreshSeconds(
+		candidate.default_refresh_rate,
+	);
+	if (defaultRefreshRate === null) return null;
+	const timeRanges: RefreshSchedule["time_ranges"] = [];
+	if (Array.isArray(candidate.time_ranges)) {
+		for (const range of candidate.time_ranges) {
+			if (typeof range !== "object" || range === null) continue;
+			const { start_time, end_time, refresh_rate } = range as Record<
+				string,
+				unknown
+			>;
+			const refreshRate = parseRefreshSeconds(refresh_rate);
+			if (
+				typeof start_time !== "string" ||
+				typeof end_time !== "string" ||
+				refreshRate === null
+			) {
+				continue;
+			}
+			timeRanges.push({ start_time, end_time, refresh_rate: refreshRate });
+		}
+	}
 	return {
-		default_refresh_rate: candidate.default_refresh_rate,
+		default_refresh_rate: defaultRefreshRate,
 		time_ranges: timeRanges,
 	};
 }