[Zerotier](https://zerotier.com) is far nicer than all of them, clients (Win, macOS, GNU\Linux, OpenWrt, iOS, Android, NAS) are open-source and the hosted service allows up to 100 devices on one of unlimited networks for free. Because it emulates the ethernet layer, there is no client side configuration required and it can be used for non-IP packets (ex. DHCP). By enabling the default route permission on the client it can also be used as a gateway to the internet through a remote host on the network. All communications are e2e AES-256 with certificate-based access for private networks. Oh, and they also run a public earth network with unlimited members billed as "the global LAN party." It's a really convenient service, and the performance is good enough to be used between private clouds.