Or just WiFi via long-range & directed antennas. Would require line-of-sight though. As far as I know that would be possibly without license and you can even us

Or just WiFi via long-range & directed antennas. Would require line-of-sight though. As far as I know that would be possibly without license and you can even use encryption! I've gotten it to work over a ~2.5km distance and that was some years ago, probably things are even better now.