diff --git a/server/player/index.html b/server/player/index.html
index 27065f6..db367b0 100644
--- a/server/player/index.html
+++ b/server/player/index.html
@@ -421,6 +421,7 @@
       };
       // Browser fingerprint (survives localStorage clear)
       data.fingerprint = generateBrowserFingerprint();
+      console.log(`[register] device_id=${data.device_id || 'none'}, has_token=${!!data.device_token}, token_len=${data.device_token?.length || 0}, paired=${config.paired}, pairing_code=${data.pairing_code || 'none'}`);
       socket.emit('device:register', data);
     }
 
@@ -455,7 +456,10 @@
       if (refreshTimer) clearInterval(refreshTimer);
       refreshTimer = setInterval(() => {
         if (socket?.connected && config.deviceId && config.paired) {
-          socket.emit('device:register', { device_id: config.deviceId, device_info: {} });
+          const data = { device_id: config.deviceId, device_info: {} };
+          if (config.deviceToken) data.device_token = config.deviceToken;
+          console.log(`[refresh-register] device_id=${config.deviceId}, has_token=${!!config.deviceToken}`);
+          socket.emit('device:register', data);
         }
       }, 300000); // 5 minutes fallback
     }
diff --git a/server/player/sw.js b/server/player/sw.js
index b71f7cb..9db8fbc 100644
--- a/server/player/sw.js
+++ b/server/player/sw.js
@@ -1,4 +1,4 @@
-const CACHE_NAME = 'rd-player-v3';
+const CACHE_NAME = 'rd-player-v4';
 const CONTENT_CACHE = 'rd-content-v1';
 
 // Install: skip waiting to activate immediately
@@ -19,18 +19,39 @@ self.addEventListener('activate', (event) => {
 self.addEventListener('fetch', (event) => {
   const url = new URL(event.request.url);
 
-  // Content files (videos, images): cache on first fetch for offline playback
+  // Only handle GET requests — let POST/PUT/DELETE pass through
+  if (event.request.method !== 'GET') return;
+
+  // Content files (videos, images): cache-first for offline playback
   if (url.pathname.startsWith('/uploads/content/')) {
+    // Skip range requests (video seeking) — serve from network, don't cache partial responses
+    if (event.request.headers.get('range')) {
+      return; // Let the browser handle range requests directly
+    }
+
     event.respondWith(
-      caches.match(event.request).then(cached => {
-        if (cached) return cached;
-        return fetch(event.request).then(response => {
-          if (response.ok) {
-            const clone = response.clone();
-            caches.open(CONTENT_CACHE).then(cache => cache.put(event.request, clone));
-          }
-          return response;
-        }).catch(() => new Response('Offline', { status: 503 }));
+      caches.open(CONTENT_CACHE).then(cache =>
+        cache.match(event.request, { ignoreSearch: true }).then(cached => {
+          if (cached) return cached;
+          return fetch(event.request).then(response => {
+            // Only cache successful, complete (non-opaque) responses
+            if (response.ok && response.status === 200 && response.type !== 'opaque') {
+              cache.put(event.request, response.clone());
+            }
+            return response;
+          }).catch(() => {
+            return new Response('Content unavailable offline', {
+              status: 503,
+              statusText: 'Service Unavailable',
+              headers: { 'Content-Type': 'text/plain' }
+            });
+          });
+        })
+      ).catch(() => {
+        // Cache API itself failed — fall through to network
+        return fetch(event.request).catch(() =>
+          new Response('Offline', { status: 503, headers: { 'Content-Type': 'text/plain' } })
+        );
       })
     );
     return;
@@ -40,16 +61,24 @@ self.addEventListener('fetch', (event) => {
   if (url.pathname.startsWith('/player') || url.pathname === '/socket.io/socket.io.js') {
     event.respondWith(
       fetch(event.request).then(response => {
-        if (response.ok) {
+        if (response.ok && response.type !== 'opaque') {
           const clone = response.clone();
           caches.open(CACHE_NAME).then(cache => cache.put(event.request, clone));
         }
         return response;
-      }).catch(() => caches.match(event.request).then(cached => cached || new Response('Offline', { status: 503 })))
+      }).catch(() =>
+        caches.match(event.request, { ignoreSearch: true }).then(cached =>
+          cached || new Response('Offline', {
+            status: 503,
+            statusText: 'Service Unavailable',
+            headers: { 'Content-Type': 'text/plain' }
+          })
+        )
+      )
     );
     return;
   }
 
-  // Everything else: network only
-  event.respondWith(fetch(event.request));
+  // Everything else: network only, don't intercept failures
+  // (Returning without calling event.respondWith lets the browser handle it natively)
 });
diff --git a/server/ws/deviceSocket.js b/server/ws/deviceSocket.js
index e8f3efc..0b1316a 100644
--- a/server/ws/deviceSocket.js
+++ b/server/ws/deviceSocket.js
@@ -182,7 +182,7 @@ module.exports = function setupDeviceSocket(io) {
         if (device) {
           // Validate device token (skip for legacy devices that don't have a token yet)
           if (device.device_token && !validateDeviceToken(device_id, device_token)) {
-            console.warn(`Invalid device token for ${device_id} from ${getClientIp(socket)}`);
+            console.warn(`Invalid device token for ${device_id} from ${getClientIp(socket)} — received_len=${(device_token || '').length}, stored_len=${device.device_token.length}, received_prefix=${(device_token || '').substring(0, 8)}, stored_prefix=${device.device_token.substring(0, 8)}`);
             socket.emit('device:auth-error', { error: 'Invalid device token' });
             return;
           }