diff --git a/web/src/pages/NePage.tsx b/web/src/pages/NePage.tsx
index 3495ffd..67c0c3b 100644
--- a/web/src/pages/NePage.tsx
+++ b/web/src/pages/NePage.tsx
@@ -349,7 +349,11 @@ export function NePage() {
                     {row.connect_status}
                   </span>
                 </td>
-                <td>{row.connect_tested_at ? formatSystemTime(row.connect_tested_at) : t("common.empty")}</td>
+                <td>
+                  {row.connect_tested_at
+                    ? formatSystemTime(row.connect_tested_at, { assumeUtcNaive: true })
+                    : t("common.empty")}
+                </td>
                 <td className="table-actions">
                   <button type="button" className="link-btn" onClick={() => openEdit(row)}>
                     {t("managedNe.edit")}
diff --git a/web/src/utils/time.ts b/web/src/utils/time.ts
index fe90c3a..1d42c7a 100644
--- a/web/src/utils/time.ts
+++ b/web/src/utils/time.ts
@@ -1,8 +1,26 @@
 const systemTimeZone = Intl.DateTimeFormat().resolvedOptions().timeZone;
 
-export function formatSystemTime(value: string | number | Date | null | undefined): string {
+type FormatTimeOptions = {
+  /** Treat timezone-less ISO timestamp strings as UTC. */
+  assumeUtcNaive?: boolean;
+};
+
+function normalizeTimeInput(value: string | number | Date, options?: FormatTimeOptions): string | number | Date {
+  if (!options?.assumeUtcNaive || typeof value !== "string") return value;
+  const text = value.trim();
+  if (!text) return value;
+  // Match "YYYY-MM-DDTHH:mm:ss(.sss)" without explicit timezone offset.
+  const isIsoLike = /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:\.\d+)?$/.test(text);
+  return isIsoLike ? `${text}Z` : value;
+}
+
+export function formatSystemTime(
+  value: string | number | Date | null | undefined,
+  options?: FormatTimeOptions,
+): string {
   if (value === null || value === undefined) return "";
-  const d = value instanceof Date ? value : new Date(value);
+  const normalized = normalizeTimeInput(value, options);
+  const d = normalized instanceof Date ? normalized : new Date(normalized);
   if (Number.isNaN(d.getTime())) return String(value);
   return d.toLocaleString(undefined, {
     hour12: false,