diff --git a/diagnostic/index.html b/diagnostic/index.html
index 3cc3db6..4f363bd 100644
--- a/diagnostic/index.html
+++ b/diagnostic/index.html
@@ -244,7 +244,7 @@
 
       <div style="border:1px solid #1E1E2E;border-radius:6px;padding:10px;">
         <div style="color:#E0E0F0;font-weight:600;margin-bottom:6px;">FritzBox (TR-064)</div>
-        <input id="dc-fb-user" placeholder="FritzBox-Benutzer" style="width:100%;margin-bottom:4px;">
+        <input id="dc-fb-user" placeholder="FritzBox-Benutzer (optional, leer wenn keiner)" style="width:100%;margin-bottom:4px;">
         <input id="dc-fb-pass" type="password" placeholder="FritzBox-Passwort" style="width:100%;">
       </div>
 
@@ -4649,8 +4649,11 @@
       }
       const hu = document.getElementById('dc-http-user').value.trim();
       if (hu) creds.http = { user: hu, pass: document.getElementById('dc-http-pass').value };
+      // FritzBox: Benutzer optional (Password-only-Boxen haben keinen) — es reicht
+      // ein Passwort. Gespeichert wird, sobald User ODER Passwort gesetzt ist.
       const fu = document.getElementById('dc-fb-user').value.trim();
-      if (fu) creds.fritzbox = { user: fu, pass: document.getElementById('dc-fb-pass').value };
+      const fp = document.getElementById('dc-fb-pass').value;
+      if (fu || fp) creds.fritzbox = { user: fu, pass: fp };
       if (!Object.keys(creds).length) { document.getElementById('dc-status').textContent = 'Nichts zu speichern — mindestens einen Typ ausfuellen.'; return; }
       send({ action: 'sat_creds_set', satellite: credsModalSat, ip: credsModalIp, creds });
       document.getElementById('dc-status').textContent = 'Speichere …';