We are an agricultural technology startup, we develop and provide advanced solutions like hydroponics etc. We are based in Egypt, Africa; where the most you can wish for is FTTC, regardless, the neighborhood we are in won't be getting FTTC until the end of the year. We have VDSL over copper wires.
The issue I am facing atm is that the office is on an 8.5 acre land, the telephone relay box is at the front gate and the office building is approximately 420 meters away from the box, connected above ground via a single UTP copper wire. As a result, the signal quality deteriorates significantly by the time it reaches the router/modem. Here are some numbers that I picked up a couple of days ago through the current router provided by the ISP.
At the box:
Noise Margin (Up/Down) : 5.1/10.5 dB
Line Attenuation (Up/Down) : 17/37.5 dB
Output Power (Up/Down): 6.1/13.2 dB
At the office:
Noise Margin (Up/Down) : 5/5.9 dB
Line Attenuation (Up/Down) : 16.4/42.7 dB
Output Power (Up/Down): 6.2/14.4 dB
So, one solution I thought of is to get a decent new router and place it near the front gate, connect a media converter through a gigabit LAN port with cat6 and use an underground shielded fiber optics cable to reach an unmanaged switch at the office.
Another solution that an acquaintance recommended is to install two managed switches, one near the front gate and the other at the office, connected through two underground shielded cat6 cables and create a trunk I believe?
I am not sure if these are good solutions or if there are better routes to go. I am not a networks professional, I just have some little knowledge and we don't have a specialized IT personnel. We are looking for connection stability most of all for at most a 100 users, currently 60.
TL;DR: UTP telephone copper wire extends over 400 meters to reach the router (office), internet stability is horrible and unusable, need help figuring out how to fix the issue.