diff --git a/app/templates/index.html b/app/templates/index.html
index f6c0b32..5cc67d4 100644
--- a/app/templates/index.html
+++ b/app/templates/index.html
@@ -222,6 +222,7 @@
   const allRows = [...document.querySelectorAll('#ap-table-body tr')];
 
   let ipFilterActive = false;
+  let ipMatchedMacs = new Set(); // AP MACs that have a client with a .150–.155 IP
 
   function isTargetIp(ip) {
     if (!ip) return false;
@@ -229,6 +230,8 @@
     return last >= 150 && last <= 155;
   }
 
+  function normMac(s) { return (s || '').toUpperCase().replace(/-/g, ':'); }
+
   function applyFilters() {
     const q = filterInput.value.toLowerCase().trim();
     let shown = 0;
@@ -240,7 +243,7 @@
       let ipMatch = true;
       if (ipFilterActive) {
         const cb = row.querySelector('.ap-checkbox');
-        ipMatch = isTargetIp(cb?.dataset.ip || '');
+        ipMatch = ipMatchedMacs.has(normMac(cb?.dataset.mac));
       }
 
       const visible = nameMatch && ipMatch;
@@ -254,8 +257,9 @@
   filterInput.addEventListener('input', applyFilters);
 
   // ── IP range filter button ─────────────────────────────────────────────────
-  const btnIpFilter  = document.getElementById('btn-ip-filter');
-  const ipFilterLabel = document.getElementById('ip-filter-label');
+  const btnIpFilter   = document.getElementById('btn-ip-filter');
+  const ipFilterLabel  = document.getElementById('ip-filter-label');
+  const ipFilterIcon   = document.getElementById('ip-filter-icon');
 
   function setIpFilterActive(active) {
     ipFilterActive = active;
@@ -274,9 +278,48 @@
     }
   }
 
-  btnIpFilter?.addEventListener('click', () => {
-    setIpFilterActive(!ipFilterActive);
-    applyFilters();
+  btnIpFilter?.addEventListener('click', async () => {
+    if (ipFilterActive) {
+      ipMatchedMacs.clear();
+      setIpFilterActive(false);
+      applyFilters();
+      return;
+    }
+
+    btnIpFilter.disabled = true;
+    ipFilterLabel.textContent = 'Loading…';
+    ipFilterIcon.classList.add('animate-spin');
+
+    try {
+      // Collect each AP's mac + site_key from the DOM checkboxes
+      const apList = [];
+      allRows.forEach(row => {
+        const cb = row.querySelector('.ap-checkbox');
+        if (cb?.dataset.mac && cb?.dataset.siteKey) {
+          apList.push({ mac: cb.dataset.mac, siteKey: cb.dataset.siteKey });
+        }
+      });
+
+      // Fetch clients for every AP in parallel (reuses the same endpoint as the popup)
+      const hits = await Promise.all(apList.map(async ({ mac, siteKey }) => {
+        try {
+          const res = await fetch(`/api/ap-clients?mac=${encodeURIComponent(mac)}&site_key=${encodeURIComponent(siteKey)}`);
+          if (!res.ok) return null;
+          const { clients } = await res.json();
+          return (clients || []).some(c => isTargetIp(c.ip)) ? normMac(mac) : null;
+        } catch { return null; }
+      }));
+
+      ipMatchedMacs = new Set(hits.filter(Boolean));
+      setIpFilterActive(true);
+      applyFilters();
+    } catch (e) {
+      showToast('Failed to load client data', 'error');
+      ipFilterLabel.textContent = 'Filter .150–.155';
+    } finally {
+      btnIpFilter.disabled = false;
+      ipFilterIcon.classList.remove('animate-spin');
+    }
   });
 
   // ── Refresh ────────────────────────────────────────────────────────────────