diff --git a/frontend/src/api/config.js b/frontend/src/api/config.js
index 7673e3c..f2e645c 100644
--- a/frontend/src/api/config.js
+++ b/frontend/src/api/config.js
@@ -1 +1,20 @@
-export const API_BASE = import.meta.env.VITE_API_BASE || "/v1";
+const DEFAULT_API_BASE = "/v1";
+
+/**
+ * API origin for fetch(): root-relative prefix (e.g. /v1) or absolute URL (https://host/v1).
+ * Root-relative values are forced to start with "/" so requests work from any SPA route
+ * (e.g. /support); otherwise "v1/support" would resolve under the current path and 404.
+ */
+function normalizeApiBase(raw) {
+  const s = String(raw ?? "").trim();
+  const base = s || DEFAULT_API_BASE;
+
+  if (/^https?:\/\//i.test(base)) {
+    return base.replace(/\/+$/, "") || DEFAULT_API_BASE;
+  }
+
+  const path = base.startsWith("/") ? base : `/${base}`;
+  return path.replace(/\/+$/, "") || DEFAULT_API_BASE;
+}
+
+export const API_BASE = normalizeApiBase(import.meta.env.VITE_API_BASE);
diff --git a/frontend/src/api/support.js b/frontend/src/api/support.js
index cfe03e7..fc40f6f 100644
--- a/frontend/src/api/support.js
+++ b/frontend/src/api/support.js
@@ -15,7 +15,7 @@ export async function submitSupportRequest({ email, description }) {
       if (data.message) message = data.message;
       else if (data.error && res.status) message = `${data.error} (${res.status})`;
     } catch {
-      message = `Request failed (${res.status}). Is the API running on port 3001?`;
+      message = `Request failed (HTTP ${res.status}). The server did not return JSON — check that POST ${API_BASE}/support is proxied to your Go API (e.g. nginx location /v1/).`;
     }
     throw new Error(message);
   }