CNET If you're an Apple TV fan, a  virtual private network  (VPN) can expand its capabilities, and as a bonus, improve your privacy and security at the same time. VPNs provide a layer of encryption, mask your IP address, and make it more difficult for marketers to track you. If you're using one with Apple TV, you may also be able to access  content libraries  that are usually unavailable in your home region by switching your IP address to one in another country. Many of the most popular VPN providers have released native Apple TV apps, making installation a breeze. Alternatively, you can install a VPN directly on your router for blanket home coverage that includes more devices, including your laptop, smartphone, and smart TV .  In ZDNET's latest update, we conducted new speed tests and performed a thorough editorial update of our guide. Get more in-depth ZDNET tech coverage:  Add us as a preferred Google source  on Chrome and Chromium browsers.…