Why not a Unifi US-8?

Is there a way to see if it is the termination or if The cable got damaged while routing it.

Yes.

Better testers have a “cable length” mode, this can show approximately where the signal is interrupted.

1. Mid-priced cable testers, when they offer this mode, use capacitance. This is inexact, but will likely suffice for your needs.

2. Expensive test tools may instead have a Time Domain Reflectometer (TDR). Prices range from a couple hundred bucks to well into the thousands.

Either way, test the cable from each end, and if the length of the faulty pair is different when testing from one termination than from the other, that should tell you if the problem is in the termination or in the wall.

What you are looking for is an “Access Point”, this is basically like a router except specifically designed to connect via Ethernet and broadcast a WiFi signal, but not do any NAT or routing or modem-like behavior.

Another term to look for is “wired backhaul network extender”. Some ISPs may have a recommendation for specific devices to serve this role and known to interoperate with their “modem”.

What’s the ‘buying old server hardware’ version? Ideally something I could pull stats from and record monthly usage.

The cheapest way to get your sum-total consumption with granularity in the range of perhaps 5 minutes would be to use an RTL-SDR (around $15) to listen to the data transmitted by many utility meters.

Next step up to collect per-circuit usage might be to purchase something like Emporia Vue.

I think the best approach is to go with standard “linked” detectors with hardwired signal+power, and then for automation you can get a “bridge” to will forward the signal from the wire to your home automation system.

If you only have a few devices, you’re overpaying if your main PC link speed is significantly below your ISPs claimed speed.

Here’s how I get link speeds on Windows:

wmic nic where netEnabled=true get name, speed

powershell "Get-NetAdapter | select interfaceDescription, name, status, linkSpeed"

If you run a CAT5E/CAT6 ethernet cable from your PC to your router, you should see a link speed of 1000000000 (same as 1000Mbps or 1Gbps).

Assuming a quality managed 2.5gbps switch, this topology should be no problem.

(FYI, the terminology “Layer 1” etc has special meaning in networking, might want to choose a different way of denoting your segmentation)

If you are using your ISPs device as your router, they see the MAC (hardware) address of each device on your wired and wireless network and know the make of each.

If you substitute your own router, the MAC isn’t passed through and they’d have a tougher time knowing exactly how many and what kind of devices are in your home network.

Additionally, some routers (and all OpenWRT routers) can run a “full tunnel VPN” client, obfuscating your traffic from your ISP’s deep packet inspection and preventing them from enumerating your internal clients.

Some “cable tester” devices offer a pair-by-pair cable length test, the inexpensive models accomplish this via simple capacitance.