My Son who is in the Internet business has a house that only had 3/4Mbps ADSL with no chance of fibre in the future so he has linked his house to a friends 2Kms away who has a 300Mbps Fibre connection,they fitted a small antenna on the aerial poles at each house and a router at my sons, took them a couple of hours to install and approx 200€ in materials,result is my son has almost 100Mbps connection and instead of paying 50€ a month to Telefonica now pays his mate 25€ they split the equipment cost which is recovered over 4 months and after that both save 25€ a month. They checked the Fibre Contract and couldn't find any clauses over reselling so they assume its legal.I am sure the Internet providers will hate this concept but they are greedy and deserve all they get..Anyone else done this?
Whilst this is possible, in many instances it is not - as to use the method above you would need 100% clear line of sight between the 2 transmission points - so unless you are very lucky with your location, to have people 2 km's apart with regular antennas on their roof's is not going to happen in any built-up area.
There are other factors, such as - Torrevieja has the most microwave localised interference levels probably in Europe - over 100 companies transmitting in this manner, so even if you do have a clear line of sight in some locations, there is a lot of interference noise, which will serve to impact the performance/speed. Our technicians used to see this when installing internet systems, in some locations they could not get any signal (even with a direct line of sight), sometimes they would get a signal, but much reduced, so the internet speed was much slower than it should have been (All Torrevieja)
If neighbours close by and nothing in the way, then possible. But I am not sure how easy it is to get 100Mbps connection as stated over 2kms by this method as soon as turned into radio frequency, usually much slower - point to point usually max out at 20Mbps odd. Perhaps your son as using some new equipment - I will concede I may not be 100% up to date!! If he has gotten these speeds - it must be a combination of the right equipment and some really good luck, certainly with location/s.
You can easily share a fast fibre via cable - if you live on a community, it may be possible to run ethernet cable down the communication ducts and share your connection with one of your neighbours, this is pretty straightforward to do.