I would check out both ZeroTier and TailScale which are very similar products. They both have a free tier you would easily fit into with 50 and 20 devices on the free plan. Essentially both allow you to setup your own private VPN service where you setup and control the clients and use of your VPN. It's rather elegant in how they work. Your first node will the the Emby Server machine. Your Emby Server node machine opens a port to their server and basically lays dormant until a client you