Double-check that the firmware version matches your hardware sticker (e.g., trying to put V5 firmware on a V4 router will fail).
After a major firmware update, it is often a good idea to reset your router to factory settings (via the web interface under System Tools > Factory Defaults) to ensure the old settings don't conflict with the new software code. Just remember to have your ISP username/password handy if you use PPPoE connection type! tenda f6 firmware update link
for the most recent F6 firmware version to see what has changed? Double-check that the firmware version matches your hardware