A VPN may improve the streaming quality of Interstellar in certain situations, but it depends on various factors. If you're experiencing slow streaming speeds due to throttling by your internet service provider (ISP), a VPN may help improve your streaming quality by bypassing ISP restrictions and allowing you to connect to faster servers in other regions. A VPN can also help reduce buffering and latency by providing a more direct and secure connection between your device and the streaming server. However, it's important to note that using a VPN may also potentially slow down your internet speed due to the added encryption and server routing.