Biggest factor is noise (thunk inductive loads like motors) on the circuits. Place your termination adapter as close to the main panel as you can and ideally on the same circuit or at least the same phase. Gfci and similar will nuke a good deal of signal.
It was a pain, but I made a matrix of every outlet and had a simple iperf server running on a raspberry pi on a lipo battery bank. I went around with a laptop and a usb eth adapter and did basic tests to get an idea of limits.
Using powerline as a single point-to-point in 2018 worked flawlessly for me with 0 drop outs, 0 latency problems, and 0 throughput problems for 4+ years and then my lines changed and it became useless.
If it works well, it can be a good way to put off the work required to hardwire.
I have a variety of Ubiquiti point-to-point setups out in the field-- AirFiber down to Nanostations. It's good gear, for sure.
For this particular application I'm concerned about being in an RF-hostile environment and unreliability, as compared to wired.
The most common approach to your situation is point to point wireless. This can be off the shelf stuff from Ubiquiti/D-Link/Whatever, to more specialized products from Aruba, Cambium, etc. Ranges of 1Km and Speeds of 1Gbps are not out of the question at all. You do need line of sight though.
Wireless (or fiber) to link buildings is also a good approach as it eliminates electrical conductivity paths across networks for lightning strikes and power surges.
Of course, this requires that you ran your electrical in conduit instead of direct-bury, so this might or might not work for you.
I enjoy getting dirty though, so I had fun hand trenching out to my shed -- didn't run water and I'm kicking myself
But, I found out during inspection that the Canadian Electrical Code prohibits this, unless the fiber is functionally related to the power lines it is running with (section 56-200).
The explanation I received for the rule, was that someone like a telco installer could try and follow the fiber line, and find themselves in a dangerous situation (inside an electrical panel they aren't trained to handle).
I was able to get an exception since I am the only one who will ever open the cabinets/work on this fiber, since it was not the main internet feed to the house, but just to an outbuilding.
And if you're really ambitious, you can run it through oil pipelines.
One of the first nationwide VOD networks was a private one run by a big oil pipeline company in Houston. I knew someone who worked on one of its daily live news shows that was transmitted that way to energy traders and oil/gas executives in offices across North America.
They made a mint selling the excess bandwidth to television stations and networks.
Pipelines are already filled with all kinds of electronics.
https://www.slb.com/products-and-services/innovating-in-oil-...
Maybe the tech has improved since then, but I suspect not.
If that doesn't work I would try two things: If the electrical cable is in a conduit or duct of some sort you could try to run a 600V rated Cat 6 cable (to comply with electrical codes) or fiber right alongside the feeders. That will not be easy as you likely have to pull the feeders, pair the network cable and then pull it back. And that is if the conduit hasn't collapsed or intruded by roots/water/dirt/etc. Second is an aerial line ran through trees or poles.
A third option is something most would avoid but just run a thin length of black poly tube with a fiber inside along the ground. Years ago a friend powered his shed at his parents countryside house by running a length of romex in a black sprinkler tube along the ground hugging the treeline of his property. Not exactly to code and illegal for power but sometimes you gotta do what you gotta do and he never had a problem.
Industrial stuff isn't far from consumer gear. Most of it uses the same components but in a rugged DIN rail or panel mount housing. Even industrial stuff is embracing wireless.
And for fiber look up BiDi - bidirectional - SFP's that use a single fiber that is easier to route. They sell rugged outdoor simplex fibers for this kind of stuff.
In the first instance, someone wanted wifi in their detached garage at the back of the lot. A couple of randomly-selected powerline adapters and an access point later, and that rig worked reliably for them for over a decade.
In the second instance, someone else wanted wifi in their detached garage at the back of the lot. A couple of randomly-selected powerline adapters and an access point later, and I couldn't make it work at all.
The main difference between these two was that one had power fed from the house's main breaker panel, and the other had power fed directly from the same transformer that the house was using but it had its own service entrance (and meter).
This anecdotally suggests it can work, and that security is inherently enhanced by not allowing the neighbors to poke at it at all (if I can't use it because there's a transformer on the loop, then the layperson next door can't use it either).
However: At my own place with my own detached garage at the back of the lot, I just use some fairly minimum-effort wifi. I've got a Mikrotik access point in a central spot in the house, and another one in the garage that acts as both a wifi client and a wifi access point (and an ethernet bridge).
Works fine. Speeds are in the >100 megabit range in both directions, which is a whole fuckton of bandwidth for anything I intend to do out there.
If the garage were far-enough away, I'd enhance this by mounting the requisite mikrotik hardware on the outside walls instead of the inside walls. If the garage were way, way out there, then I'd use different mikrotiks with directional antennas to backhaul, and additional radios indoors for wifi coverage.
If I had more than one outbuilding, then I might use a one-to-many topology with an omni at the house and directional antennas on the outbuildings.
(I made an extra SSID that was just for the garage to keep the dumb devices out there from wandering onto the house's access point for whatever dumb reason they elect to do that, but meh: They'd still do dumb shit like that even if I were to string fiber.)
More words: no really don’t. Either do wireless or bury some fiber depending on needs.
Lower latency, more stable, and higher bandwidth. (The av2 ones would just drop out for 90-ish seconds a few times a month, which was quite annoying).
It's interesting the article talks about home plug av2 and g.hn coexisting, when my experience has been that g.hn powerline is much better, and it feels like g.hn is generally perceived as a successor to av2 in the UK.
Edit: also, I'm in agreement with other folk in that point-to-point wireless is the solution I most often see used in that case, or sometimes fibre.
Edit2: and it's also probably the cheapest one to test. If it's not good enough, then you know you're looking at wireless or fibre.
When you try to use as much bandwidth as you can, they fail in sometimes spectacular ways. I have some old Radio Shack 10 Mbps ones that have brought a high end Juniper to its knees when the Radio Shack box's "collision" LED was fully lit. Newer devices do better, but it's best to just use powerline networking for things that need steady, continuous traffic.
IEEE 1901 is only specified for 500Mbps though. The more industrial use-cases are rarely high-bandwidth and that market is often pretty satisfied with even Kbps performance, they're just sending Modbus and that sort of thing. IEEE 1901 equipment is also going to be quite a bit more expensive to obtain since the market is small and mostly works on large contracts.
I agree with others that point-to-point wireless is probably your best bet. It can be similarly priced to HomePlug AV2 transceivers and, sort of ironically, will probably turn out to be more reliable. HomePlug tends to have trouble when there are neutral bonds because that adds "side legs" to the bus that harbor reflections. That's why people tell you that, as a rule of thumb, your transceivers need to be on the same circuit for good performance. It's a particularly bad with an outbuilding scenario because you've probably got two panels with two neutral buses, adding two different sets of reflections. Hard for the modulation scheme to contend with. I've personally run HomePlug AV1 from a house to a pump shed with a subpanel and got ~15Mbps performance with near-total dropout when the pump was running. ymmv depending on the wiring.
You might also consider direct-burial Ethernet, which is not very expensive. However, you'll get into some complexities with bonding and lightning protection and you might need to study the code book a bit. Some people will insist that one must never connect separate buildings with metallic communications conductors, but I would remind them that until about the 1980s that was the only way to do it, and techniques and equipment to do it safely have been developed. You just have to, you know, learn and use them.
Regarding privacy, I've always wondered about this regarding ethernet over power lines. Surely the signal must leak to some extent to nearby houses on the same grid?
* You will not get reliability. Ethernet over power lines are notorious for developing problems related to power line load, topography and switching.
* You will not get privacy. The ethernet signal does not magically stop at "your" power network, but commonly escapes and can be picked up at other houses down the street from you.
Seriously, forget it. There is a reason Wi-Fi is more popular.
I have an application to network a couple of outbuildings. I don't have tremendous bandwidth needs (1Gbps would be glorious, 100Mbps would be fine). I would prefer wired connections for reliability and privacy. I would prefer not to trench and run fiber. The outbuildings already have electrical service from a central panel. Powerline networking might be a good fit.
There's a lot of consumer stuff out there. I'd like something a little more geared toward an industrial, commercial, or service provider use. (Analogously, think of the difference between using a dumb Netgear switch versus a managed name-brand managed switch.)
Edit: I appreciate the feedback I'm hearing here. This is exactly the kind of stuff I wanted to hear. Sorry to hijack HN for my personal needs like this!