diff --git a/haos-addon/src/web/index.html b/haos-addon/src/web/index.html
index 4f10bc5..16aa457 100644
--- a/haos-addon/src/web/index.html
+++ b/haos-addon/src/web/index.html
@@ -379,6 +379,10 @@ let currentConfig = {};
 let inverterList = {};
 let refreshTimer = null;
 
+// Basis-URL relativ zur aktuellen Seite (funktioniert hinter HA Ingress-Proxy)
+const BASE = new URL("./", window.location.href).pathname;
+function apiUrl(path) { return BASE + path; }
+
 async function fetchJSON(url, opts) {
   const r = await fetch(url, opts);
   if (!r.ok) throw new Error(`HTTP ${r.status}`);
@@ -408,7 +412,7 @@ function switchTab(name) {
 // ── Live data ──
 async function refreshData() {
   try {
-    const d = await fetchJSON("/api/data");
+    const d = await fetchJSON(apiUrl("api/data"));
     updateStatus(d.modbus_ok, d.mqtt_ok);
     updateSubtitle(d);
     updateInfoRow(d);
@@ -479,7 +483,7 @@ function stopRefresh() {
 // ── Config ──
 async function loadConfig() {
   try {
-    currentConfig = await fetchJSON("/api/config");
+    currentConfig = await fetchJSON(apiUrl("api/config"));
     fillForm(currentConfig);
   } catch (e) {
     showToast("Konfiguration konnte nicht geladen werden", "err");
@@ -488,7 +492,7 @@ async function loadConfig() {
 
 async function loadInverters() {
   try {
-    inverterList = await fetchJSON("/api/inverters");
+    inverterList = await fetchJSON(apiUrl("api/inverters"));
     buildInverterGrid(inverterList, currentConfig.inverter_model);
   } catch (e) {}
 }
@@ -541,7 +545,7 @@ async function saveConfig(e) {
   };
 
   try {
-    await fetchJSON("/api/config", {
+    await fetchJSON(apiUrl("api/config"), {
       method: "POST",
       headers: { "Content-Type": "application/json" },
       body: JSON.stringify(body),