Are you sure that it’s two cables and not just one that loops back?
Use an Ethernet cable tester/tracer to find where they end up.
Reusing the cable seems like a no brainer, but you may find the cable is already setup like that. Use the tracer.
This seems to be coaxial cable ISP. They are terrible
One option is to run a cable between the locations, either Cat6 or Multimode Fiber if the location is further than 100m.
Another option is using a Wireless link. There are fixed wireless devices that have directed beams to reach out up to 10km distance between nodes.
Ubiquiti has a product called Nanobean that is quite popular and that you can use in this scenario.
In the Fiber or Wireless link option, it is assumed there are power outlets on both ends of the link. If power is only available on one end, then you could double down on Cat6, use PoE extenders to be able to run a Cat6 cable over 100m, and then have an PoE powered access point given enough power is left at the end of the cable run.
Powerline IS TERRIBLE. It’s better to use WiFi than Powerline.
Is coaxial running at your place? You could use MoCA adapters in place of the Powerline ones, and its reliability is great, almost as fast as wired Ethernet.
There is a lot of variance in the amount of work involved, but as a general rule:
Get a Bill of Materials so you can independently quote them. I did buy all the materials when I did put my wired Ethernet home network.
Estimate about 1.5h per port x 2 folks x 45usd/hr. The amount of total hours spent and the amount of people they need to bring (they would at least need two) are the next big thing. The hourly rate depends on your local labor market.
It depends on which devices he had access to. If he was using your computer, he could potentially access your full history, but you would’ve been able to see him do it.
If he was just using your router, it would be highly unlikely he was able to review your history. However, if you’re a high-value target (someone trading with bitcoins or something like that), an hostile party could pretend being from the ISP to try to infiltrate your network.
Cancel the service and get Fiber optics.