diff --git a/server.ts b/server.ts
index f93bdc2..ce3f773 100644
--- a/server.ts
+++ b/server.ts
@@ -741,50 +741,38 @@ async function startServer() {
     }
 
     // Step 2: fetch live monitoring state for all hosts in one call.
-    // Uses query param to force the collection to return results (some CheckMK versions
-    // return an empty list without an explicit filter even with full permissions).
     let hostnameToState: Map<string, number>;
     try {
-      const monQuery = encodeURIComponent(JSON.stringify({ op: '!=', left: 'name', right: '' }));
       const monRes = await fetch(
-        `${CHECKMK_API_URL}/domain-types/host/collections/all?query=${monQuery}`,
+        `${CHECKMK_API_URL}/domain-types/host/collections/all`,
         { headers }
       );
       if (!monRes.ok) throw new Error(checkmkHttpHint(monRes.status));
       const monData = await monRes.json();
+
+      // Log raw response so we can see the actual structure (first 500 chars).
+      db.prepare('INSERT INTO logs (id, timestamp, type, message) VALUES (?, ?, ?, ?)')
+        .run(uid('log'), now, 'system',
+          `CheckMK monitoring raw response: ${JSON.stringify(monData).substring(0, 500)}`);
+
       hostnameToState = new Map<string, number>();
-      for (const host of monData?.value ?? []) {
-        const name: string | undefined = host?.id;
+      // Try multiple possible container keys used by different CheckMK versions.
+      const candidates: any[] = Array.isArray(monData?.value)
+        ? monData.value
+        : Array.isArray(monData?.members)
+          ? monData.members.map((m: any) => m?.value ?? m)
+          : [];
+      for (const host of candidates) {
+        const name: string | undefined = host?.id ?? host?.extensions?.name;
         const state: number | undefined = host?.extensions?.state;
         if (name !== undefined && state !== undefined) hostnameToState.set(name, state);
       }
 
       if (hostnameToState.size === 0 && ipToHostname.size > 0) {
-        // Monitoring collection empty despite config hosts existing.
-        // Likely cause: automation user lacks "Use monitoring" permission in CheckMK.
-        // Falling back: probe one host via /objects/host_config/{name} and log its raw extensions
-        // so we can identify which field carries the reachability state.
         db.prepare('INSERT INTO logs (id, timestamp, type, message) VALUES (?, ?, ?, ?)')
           .run(uid('log'), now, 'system',
-            'CheckMK: monitoring collection returned 0 hosts — automation user has no monitoring view access. ' +
-            'Fix in CheckMK: Setup → Users → edit automation user → Roles → assign "Administrator" or a role with ' +
-            '"General Permissions → Use monitoring" and "See all hosts and services" enabled. ' +
-            'Alternatively: add the automation user to all relevant Contact Groups.');
-
-        const firstHostname = [...ipToHostname.values()][0];
-        try {
-          const probeRes = await fetch(
-            `${CHECKMK_API_URL}/objects/host_config/${encodeURIComponent(firstHostname)}`,
-            { headers }
-          );
-          if (probeRes.ok) {
-            const probeData = await probeRes.json();
-            const extJson = JSON.stringify(probeData?.extensions ?? {}).substring(0, 400);
-            db.prepare('INSERT INTO logs (id, timestamp, type, message) VALUES (?, ?, ?, ?)')
-              .run(uid('log'), now, 'system',
-                `CheckMK probe extensions for "${firstHostname}": ${extJson}`);
-          }
-        } catch { /* probe is best-effort */ }
+            `CheckMK: parsed 0 monitoring hosts from response (candidates array length: ${candidates.length}). ` +
+            'Check the raw response entry above to identify the correct JSON path.');
       }
     } catch (err: any) {
       const msg = `CheckMK sync failed — could not fetch monitoring states: ${err?.message ?? err}`;