> firewalls, V4 NAT
That's why they added 'use UPnP to poke a hole in the router'. Which will work on most networks, though CGNAT will still break it if IPv6 isn't available.
There are plenty of other tools out there that can send files between devices. Google+Samsung's Nearby Share work pretty much everywhere. KDE Connect works on any device I can think of. I wish Google+Samsung would make it an open standard but I'm guessing they won't do it so they can rewrite the app whenever they please.
The biggest, and IMO only, problem for AirDrop competitors is that they're not pre-installed on iPhones and iPads while AirDrop is. AirDrop is nothing special in itself, though Apple did implement it in a rather weird way. All you need to mimic it is Bluetooth (BLE if you're fancy) for handshakes and WiFi Direct for transfers.
There are plenty of other tools out there that can send files between devices. Google+Samsung's Nearby Share work pretty much everywhere. KDE Connect works on any device I can think of. I wish Google+Samsung would make it an open standard but I'm guessing they won't do it so they can rewrite the app whenever they please.
The biggest, and IMO only, problem for AirDrop competitors is that they're not pre-installed on iPhones and iPads while AirDrop is. AirDrop is nothing special in itself, though Apple did implement it in a rather weird way. All you need to mimic it is Bluetooth (BLE if you're fancy) for handshakes and WiFi Direct for transfers.