@PawelK @h4890 @useless_idiot Lora and parabolic reflectors with the 2.4Ghz WiFi in the feed horn. The Lora coms can be used to align antennas for the WiFi. The distance on that setup is going to be just under 20km I think. It's limited by the transit time but the gain from the two reflectors uses off the shelf hardware without increasing TX power.

The above will make reconfigurable connections with End to End connections. To interrupt that very small beam would be rather difficult because it's designed to filter out interference. Those used satellite dishes are good for it. You can use beams or metal mesh as the reflector to make it even more resistant to interference. The biggest threat is the wind.

About the 3G, I didn't know it still was in use. Any number of used flagship phones with established TWRP and LineageOS ports can be bought for very little money because of the older network. The older flagships are going to be easy to repair too.