Running Ethernet over existing coaxial cable

> The manufactures of G.hn2 Coaxial adapters seem to be stingy about selling them to individuals.

I can find several at Amazon (Germany). For example https://www.amazon.de/GIGA-Copper-Ethernet-Netzwerk-Koaxialk...

I bought a house in a locality that requires conduit for all in-wall wiring (including low voltage) by code. This annoys most people, but I love it since it means you can upgrade stuff easily in the future if you desire.

This house did not have cat5 installed anywhere, but it had both coax and cat3 for the old school phone lines/intercom system.

During the inspection I removed some wall plates and noted that there indeed appeared to be properly installed conduit in every box I spot-checked. Inspectors noted the same.

After I moved in and got all the supplies ordered and staged to start removing coax/cat3 using them as pull strings for my expensive fancy new CAT6 wiring I found out something super fun...

The builder had decided to cheat the code inspectors by installing every single box with only about a foot of conduit attached to the boxes. After that they simply stapled the wiring to the studs every so often making pulling cable with them impossible. At least it appears they did indeed use conduit for the AC power.

Not entirely related to your point, but it's something that still makes my blood pressure increase a tick even remembering it enough to describe here.

What went from a weekend of pulling new cable with conveniently placed pull strings turned in to a month's-long ordeal of running new cat6 through the house and then another couple weeks of drywall repair for all the holes needed to do so.

There are also PoE over Coax devices if your house (like mine) was setup with NTSC security cameras: https://www.amazon.com/gp/product/B07G194BQD

This device picks up PoE power and ethernet at one end and delivers up to 21w at 100m to the remote end (less for longer runs). Enough to run most IP cameras. Speed is only 100Mbps (up to 300m, 10Mbps at 1000m) but that's more than enough for 4k live streaming.

It also supports transmission over twisted pair instead of coax. You can use that to pipe Ethernet and PoE over twisted pair doorbell or phone wire. Apparently a common usage is getting Ethernet onto older elevators over the legacy twisted pair emergency phone line. How much bandwidth and power you get depends on the quality and type of wire - in my experience it does a decent job adapting to conditions.

I will eat my hat if anyone installing coax actually uses conduits, the kind of people doing the installation -- your cable provider gives zero shits. Avoiding "sharp turns" should be no issue since in your average home you're not gonna need >4 quarter turns that would necessitate a junction box.

Cat 5 is more than adequate to do gigabit for even huge houses.

If some conductors aren't connected, have bad connections, or the order of wires is wrong, then many gigabit ports will negotiate to 100 Mbps, which only requires four working wires out of the eight.

A cable tester from Micro Center (if you're lucky enough to have one close enough to visit) is $7.99, plus a 9 volt battery (which, funnily, is about half the price of the cable tester). Amazon has the same testers for around $10.

MoCA is great, particularly if you're using cable boxes that require Internet over MoCA and you want to replace the NAT router your ISP provides, but it's a bit silly to use MoCA when you have wires that probably just need to be re-terminated or terminated properly.